In a particular experiment, a 2.00-g sample of cao is reacted with excess water and 2.14 g of ca(oh)2 is recovered. what is the percent yield in this experiment?
Final answer:
In an experiment with a 2.00-g sample of CaO reacting to form 2.14 g of Ca(OH)₂, the percent yield is calculated as more than 100%, suggesting an error in measurement or theoretical yield assumptions.
Explanation:
In this experiment, a 2.00-g sample of CaO is reacted with excess water to produce Ca(OH)₂, and 2.14 g of Ca(OH)₂ is recovered. To calculate the percent yield of this reaction, we first need to understand that percent yield is calculated using the formula: percent yield = (actual yield/theoretical yield) x 100%. However, to calculate the percent yield in this case, we will presuppose that under ideal conditions, the reaction of the 2.00 g of CaO would yield an equivalent molar amount of Ca(OH)₂.
Without going into detailed stoichiometry and assuming perfect conversion, the amount ofCa(OH)₂ produced directly mirrors the starting amount of CaO due to the 1:1 molar ratio in the reaction CaO + H2O = Ca(OH)₂. If 2.14 g of Ca(OH)2 is the actual yield and we accept the theoretical yield as 2.00 g (for simplicity, and acknowledging that the real theoretical yield would require molar mass calculations), the percent yield can be calculated as follows: percent yield = (2.14 / 2.00) x 100% = 107%.
The calculation example here demonstrates the concept of percent yield but importantly highlights that a yield over 100% indicates a discrepancy, possibly in measurement or assumption of theoretical yield without correct stoichiometric calculation.
An organic solid has a vapor pressure of 900 torr at its melting point explain how you would purify this compound
A package contains 1.33 lb of ground round. If there’s 29% fat, how many grams of fat are in the round?
Answer: 175.10 g
Explanation:
Total weight of the package = 1.33 lbs
[tex]1 lbs=454 g[/tex]
So, 1.33 lbs =[tex]1.33\times 454=603.82g[/tex]
Amount of fat in the given weight = 29%
Hence fat in grams in package =[tex]\frac{29}{100}\times 603.82=175.10 g[/tex]
Which ocean zone has the lowest water pressure?
Hadal zone
Mesopelagic zone
Abyssopelagic zone
Epipelagic zone
Answer: Epipelagic zone
Explanation:
The epipelagic zone is the zone which exists over the surface of water. It is also called as the sunlight zone as it receives the maximum and direct sunlight from the sun. It is also called as photosynthetic zone as the sunlight is utilized by the plants and small phytoplanktons to conduct photosynthesis. This zone exhibit lowest water pressure as it lies in the superficial layers of the water body.
Upon hearing a small sample of red powder, it darkens and then suddenly changes into a shiny silvery liquid. This student can conclude:
Final answer:
The student observed a chemical reaction characterized by a color change and the formation of a new substance, indicating an energy transfer. Such changes signify that the original red powder has chemically altered into a new material.
Explanation:
Based on the description of the red powder that darkens before changing into a shiny silvery liquid upon heating, the student can conclude that a chemical reaction has occurred. This conclusion is supported by several indications that a chemical change has taken place. Color change and the formation of a new substance (silver liquid from a red powder) provide evidence that original substances have been transformed into different materials with distinct properties.
Furthermore, such changes are also indicative of the possibility that energy transfer has occurred, evidenced by the exothermic reaction that produces heat. This would be consistent with the visual clues that suggest a chemical reaction is likely taking place according to provided reference summaries.
calculate the correct number of moles and formula units in 7.3x10^-3g of CaSO4
Rain puddle drying up, chemical or physical change
A rain puddle drying up is a physical change, known as evaporation, which occurs when liquid water turns into vapor due to higher temperatures and varying humidity levels.
When a rain puddle dries up, this is an example of a physical change, specifically, the process of evaporation. In this process, water transforms from a liquid state to a gaseous state; this occurs when the temperature is warm, which facilitates the movement of water molecules faster, allowing them to escape into the air. The amount of water vapor the air can hold increases with higher temperatures, and the evaporation rate is also influenced by how saturated the air is with moisture. On the other hand, sublimation is a physical change where ice turns directly into vapor without going through the liquid stage, which can occur during cold, dry conditions. Similarly, transpiration involves the physical change of water moving through a plant and evaporating into the atmosphere, and condensation is the process where water vapor turns back into liquid, such as when moisture forms on the outside of a cold water bottle.
Marsha can cook 5 cakes or 10 pizzas in an hour Howard can cook 3 cakes or 12 pizzas in a hour. Which items should each person specialize in
Calculate the number of cells in a hummingbird assuming it weighs 10-2 kg
A hummingbird weighing 10^-2 kg contains approximately one trillion cells, assuming the average cell is ten times the mass of a bacterium. For a human weighing 70 kg with the same assumption, it would contain around 7 quadrillion cells.
Explanation:To calculate the number of cells in a hummingbird assuming it weighs 10-2 kg and considering the mass of an average cell is ten times the mass of a bacterium, we first need to establish the average mass of a bacterium. From the reference information given, we understand that the mass of a bacterium is on the order of 10-15 kg. Therefore, the average cell mass would be 10 times this, which is 10-14 kg.
Next, we divide the total mass of the hummingbird by the mass of one of its cells to determine the number of cells:
Number of cells = Mass of hummingbird / Mass of one cell
Number of cells = 10-2 kg / 10-14 kg
Number of cells = 1012
Therefore, a hummingbird that weighs 10-2 kg contains approximately one trillion (1012) cells.
To address part (b) of the question, assuming a human weighs about 70 kg and also assuming the mass of a human cell is ten times the mass of a bacterium (10-14 kg), we can perform a similar calculation:
Number of cells in a human = Mass of human / Mass of one cell
Number of cells in a human = 70 kg / 10-14 kg
Number of cells in a human = 7 x 1015
This suggests that a human has around 7 quadrillion (7 x 1015) cells.
A colored solution gives the maximum absorbance value in the spectrophotometer at the wavelength of 533 nm. what are the absorbed and perceived colors of this solution?
The pka of the α-carboxyl group of methionine is 2.28, and the pka of its α-amino group is 9.21. calculate the average net charge on methionine if it is in a solution that has a ph of 8.00. if the charge is positive, do not enter a \" \" sign.
The average net charge on methionine at a pH of 8.00 will be slightly positive, as the pH is below the pKa of the α-amino group (9.21), leading to a higher proportion of protonated amino groups compared to deprotonated carboxyl groups.
Explanation:To calculate the average net charge on methionine at a pH of 8.00, we consider the ionization states of its functional groups based on their pKa values. The pKa of the α-carboxyl group is 2.28, which is significantly lower than the pH of the solution, implying that this group is in its deprotonated (negatively charged) state, -COO-. The pKa of the α-amino group is 9.21, which is higher than the pH, meaning this group is in its protonated (positively charged) form, -NH3+. For a pH between the pKa values of the two ionizable groups, the molecule carries both charges.
Using the Henderson-Hasselbalch equation, we determine the fraction of methionine molecules with a protonated amino group:
-Protonated amino group (positive charge):
pH = pKa + log([A-]/[HA])
Rearranging for [HA]/[A-], we get [HA]/[A-] = 10(pH - pKa)
[HA]/[A-] = 10(8.00 - 9.21) = 10(-1.21) = approximately 0.061.
The fraction of deprotonated carboxyl groups (-COO-) is essentially 1, since the pH is well above its pKa. Thus, nearly all methionine molecules will have one negative charge. Considering the ratio for the protonated amino group, there would be more neutral (-NH3) than positively charged (-NH2) amino groups, leading to an overall net charge that is slightly positive.
Therefore, the average net charge on methionine in a solution of pH 8.00 will be slightly positive, since the amount of protonated amino groups will outweigh the deprotonated carboxyl groups, but not by as significant an amount as if the pH were equal to the isoelectric point.
What can affect the properties of a substance
Answer:
the arrangement and types of atoms
Explanation:
Bronze is an alloy made of copper (cu) and tin (sn). calculate the mass of a bronze cylinder of radius 3.77 cm and length 35.38 cm. the composition of the bronze is 79.42 percent cu and 20.58 percent sn and the densities of cu and sn are 8.94 g/cm3 and 7.31 g/cm3, respectively. what assumption should you make in this calculation? enter your answer in scientific notation.
Final answer:
To find the mass of a bronze cylinder, calculate its volume using its dimensions, then compute the weighted average density based on the proportions of copper and tin, and finally multiply the volume by this average density. Convert to scientific notation as the last step.
Explanation:
To calculate the mass of the bronze cylinder, we must first determine its volume using the formula for the volume of a cylinder, V = πr^2h, where π is Pi, r is the radius, and h is the height or length of the cylinder. Then, we can use the composition percentages of copper (Cu) and tin (Sn) along with their densities to calculate the mass.
First, we must assume that the alloy is uniformly mixed such that the ratio of the densities corresponds exactly to the percentage composition provided. Now, let's calculate the volume:
Radius (r) = 3.77 cm
Length (h) = 35.38 cm
Volume (V) = π * (3.77 cm)^2 * 35.38 cm
Next, we calculate the contribution of each metal's mass to the total mass of the cylinder:
Density of Cu = 8.94 g/cm^3
Density of Sn = 7.31 g/cm^3
Percentage of Cu = 79.42%
Percentage of Sn = 20.58%
To find the total mass (m), we multiply the volume (V) by the weighted average density (ρ_avg), which factors in the percentages of Cu and Sn:
ρ_avg = (0.7942 * 8.94 g/cm^3) + (0.2058 * 7.31 g/cm^3)
Mass (m) = Volume (V) * ρ_avg
Lastly, the mass can be converted to scientific notation as required.
What is the theoretical yield of Na2SO4, in grams?
If you burn 23.4 g of hydrogen and produce 209 g of water, how much oxygen reacted?
Which of these is NOT a falsifiable hypothesis?
A) Species change over time.
B) Inherited characteristics are carried on factors called genes.
C) Cells come from other cells.
D) Life on earth was seeded by extraterrestrial aliens.
Answer:
D
Explanation:
The term falsifiable refers to the possibility that a theory or hypothesis can be proven wrong. Each theory has the capacity to be proven wrong through experimentation, however option D has no way of being proven wrong (even though it cannot be proven right), because this theory is about what happened before humans could keep records. So there is no way it can be proven wrong, and hence it is not a falsifiable hypothesis.
Select all the items that are related to compounds. 1.chemical bonding 2.physical change 3.maintain original physical properties 4.new physical properties 5.mixture of 2 or more elements
The correct answer is option 3 and 5.
Compounds are made up of a mixture of 2 or more elements such as H₂O or NaCl.
Compounds have physical properties that are constant and hence allow us to identify them. Different physical properties include color, solubility, mass, odor, density, boiling point, melting point etc
Answer:
The correct answers are, "Maintain Original Physical Properties", "Mixture of 2 or More Elements", and "Physical Change"
Explanation:
Identify the oxidizing agent and the reducing agent for mg(s)+fe2+(aq)→mg2+(aq)+fe(s). express your answers as chemical formulas separated by a comma.
The Mg element is the reducing agent and the Fe element is the oxidizing agent
Further explanationThe oxidation-reduction reaction or abbreviated as Redox is a chemical reaction in which there is a change in oxidation number
3 basic theories explain this Redox concept:
1. Binding/release of oxygenThe oxidation reaction is the binding of a substance with oxygen. (O₂)
For example:
2SO₂ + O₂ ----> 2SO₃
The reduction reaction is the release of oxygen from a substance.
For example:
2CuO → 2Cu + O₂
2. Electron release / binding reactionOxidation is an electron release event
Example:
2F ---> 2Fe³⁺ + 6e⁻
The reduction is an electron capture event
Example:
3O₂ + 6e⁻ ---> 3O²⁻
3. The reaction of addition/reduction of oxidation numberOxidation is an increase/increase in oxidation number, while reduction is a decrease in oxidation number.
In the redox reaction, it is also known
Reducing agents are substances that experience oxidation
The oxidizing agent is a substance that is reduced
The formula for determining Oxidation Numbers in general:
1. Single element atomic oxidation number = 0. Examples of Ar, Mg, Cu, Fe, N₂, O₂, etc. = 0
Group IA (Li, Na, K, Rb, Cs, and Fr): +1
Group IIA (Be, Mg, Ca, Sr and Ba): +2
H in compound = +1, except metal hydride compounds (Hydrogen which binds to IA or IIA groups) oxidation number H= -1, for example, LiH, MgH₂, etc.
2. Oxidation number O in compound = -2, except OF2 = + 2 and in peroxide (Na₂O₂, BaO₂) = -1 and superoxide, for example KO₂ = -1/2.
3 The oxidation number in an uncharged compound = 0,
Total oxidation number in ion = ion charge, Example NO₃⁻ = -1
Redox reactions are reactions that are accompanied by changes in oxidation numbers, so what must be examined is whether there are elements that experience changes in oxidation numbers in the reaction
Let's look at the reaction
Mg(s)+Fe²⁺(aq)→Mg²⁺(aq)+Fe(s)
Let see the change in the oxidation number of each element
Mg on the left = 0 (single element)
Fe²⁺ on the left = +2 ( ion charge)
Mg on the right = +2 ( ion charge)
Fe on the right = 0 (single element)
Means that the element Mg has increased oxidation number from 0 to +2 so that it experiences an oxidation reaction and acts as a reducing agent
While Fe has decreased the oxidation number from +2 to 0, so it has a reduction reaction and acts as an oxidizer
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Keywords: oxidation-reduction, an oxidizing agent, a reducing agent
Suppose a reaction mixture, when diluted with water, afforded 300 ml of an aqueous solution of 30 g of the reaction product malononitrile [ch2(cn)2], which is to be isolated by extraction with ether. the solubility of malononitrile in ether at room temperature is 20.0 g/100 ml, and in water is 13.3 g/100 ml. what weight of malononitrile would be recovered by extraction with (a) three 100-ml portions of ether and (b) one 300-ml portion of ether? suggestion: for each extraction, let x equal the weight extracted into the ether layer. in part (a), the concentration in the ether layer is x/100 and in the water layer is (30 x)/300; the ratio of these quantities is equal to k 20/13.3. williamson, kenneth l.; masters, katherine m.. macroscale and microscale organic experiments (available titles coursemate) (page 163). cengage textbook. kindle edition.
A three-step extraction procedure is more effective than a one-stage extraction. a) 21.11 g is the total malononitrile extracted. b) 18.07 g is the total malononitrile extracted.
In chemistry, the term "extraction" refers to the procedure of removing one or more components from a mixture based on the differences in their physical or chemical properties. This method is frequently employed to separate desired components from intricate combinations. Transferring the target substance from one phase (often a liquid phase) into another phase, where it can be more easily purified or analysed, is the aim of extraction.
Kd for malononitrile in ether/water = 20/13.3
= 1.5
(a) 1.5 = [(x/100)/(30 - x)/300]
0.15 - 0.005x = 0.01x
x = 10 g
amount left in water = 30 - 10
= 20 g
1.5 = [(x/100)/(20 - x)/300]
0.1 - 0.005x = 0.01x
x = 6.67 g
amount left in water = 20 - 6.67
= 13.33 g
1.5 = [(x/100)/(13.33 - x)/300]
0.067 - 0.005x = 0.01x
x = 4.44 g
amount left in water = 13.33 - 4.44
= 8.89 g
Total malononitrile extracted = 21.11 g
(b) 1.5 = [(x/300)/(30 - x)/300]
0.15 - 0.005x = 0.0033x
x = 18.07 g
amount of malononitrile extracted = 18.07 g
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Final answer:
To recover malononitrile by ether extraction, multiple smaller extractions are generally more efficient due to the solubility dynamics and distribution ratio between ether and water. This efficiency is owing to the partition coefficient (K) that favors the transfer of malononitrile into the ether phase, allowing for better separation and recovery.
Explanation:
To calculate malononitrile recovery by extraction with ether, we utilize its distribution ratio (K) derived from solubility data in ether and water. The solubility of malononitrile in ether at room temperature is 20.0 g/100 ml, and in water, it's 13.3 g/100 ml, giving K = 20/13.3.
Part A: Three 100-mL Portions of Ether
For each 100-mL extraction, we calculate the weight of malononitrile extracted into the ether, x, using an iterative process:
First extraction: x = weight of malononitrile moved to ether layerSecond extraction: repeat with remaining aqueous phaseThird extraction: final iterationMathematically, this considers solute partitioning for each step and re-calculates the residual amount in water.
Part B: One 300-mL Portion of Ether
The extraction with one 300-mL portion uses the total volume of ether to extract the malononitrile at once. This method may not be as efficient as multiple extractions due to the diminishing marginal returns on mass transferred per unit of solvent as the solvent becomes saturated.
Ultimately, the mass of malononitrile recovered is influenced by the distribution ratio, the volume of ether, and the strategy of extraction, showing that multiple smaller extractions are generally more efficient than a single, large-volume extraction.
What is the concentration of k+ ions in a 0.025 m k2co3 solution assuming complete dissociation?
The complete dissolution of 0.025 M [tex]\rm K_2CO_3[/tex] will result in 0.050 M [tex]\rm K^+[/tex].
The complete dissolution of [tex]\rm K_2CO_3[/tex] will result in:
[tex]\rm K_2CO_3\;\rightarrow\;2\;K^+\;+\;CO_3^2^-[/tex]
1 molecule of [tex]\rm K_2CO_3[/tex] will gives 2 molecules of [tex]\rm K^+[/tex].
So 0.025 M [tex]\rm K_2CO_3[/tex] will give: 1 M
0.025 M [tex]\rm K_2CO_3[/tex] = [tex]\rm 0.025\;\times\;2\;K^+[/tex] M
= 0.05 M [tex]\rm K^+[/tex].
Thus the complete dissolution of 0.025 M [tex]\rm K_2CO_3[/tex] will result in 0.050 M [tex]\rm K^+[/tex]
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What ratio of reactants (cyclohexane and chlorine) would you use for the synthesis of chlorocyclohexane?
When discussing acids and bases, any substance that accepts a proton, by definition, is considered
A mixture was found to contain 3.50 g of sugar, 4.80 g of NaCl, and 7.20 g of sand. What is the percentage of sand?
First get the sum of the mass of each substance.
total mass = 3.50 g + 4.80 g + 7.20 g
total mass = 15.50 g
The percentage mass would be:
% mass = (7.20 g / 15.50 g) * 100%
% mass = 46.45%
a bottle of liquid acetone is converted to a gas at 75.0 C. if 628 J are required to raise the temperature of the liquid to the boiling point, 15.600 kJ are required to evaporate the liquid, and 712 J are required to raise the final temperature to 75.0 C, what is the total energy required for the conversion?
Aqueous solutions of barium nitrate and potassium phosphate are mixed. What is the precipitate and how many molecules are formed?
Answer: The precipitate is [tex]Ba_3(PO_4)_2[/tex] and 1 molecule of Barium phosphate and 6 molecules of Potassium nitrate is formed.
Explanation: We are given Barium nitrate and Potassium phosphate , that will lead to the formation of Barium phosphate and Potassium nitrate.
As we know that these solutions are present in water, therefore we will obtain Barium phosphate as a precipitate because Barium phosphate is insoluble in water and Potassium nitrate is soluble in water. Thus the reaction is
[tex]Ba(NO_3)_2(aq.)+K_3PO_4(aq.)\rightarrow Ba_3(PO_4)_2(ppt.)+KNO_3(aq.)[/tex]
To know how many molecules are formed at the end, we need to balance the above equation.
Balancing the equation, we get:
[tex]3Ba(NO_3)_2(aq.)+2K_3PO_4(aq.)\rightarrow Ba_3(PO_4)_2(ppt.)+6KNO_3(aq.)[/tex]
Thus, we get 1 molecule of Barium phosphate as a precipitate and 6 molecules of Potassium nitrate which is easily soluble in water.
Answer:
The barium phosphate is precipitate and 1 molecule is formed.
According to the reaction mentioned,
[tex]\rm \bold { 3BaNO_3_(_a_q_)+ 2K_3PO_4_(_a_q_) \rightarrow Ba_3(PO_4)_2_(_p_p_t_)+ 6 KNO_3_(_a_q_)}[/tex]
We can conclude that, the barium phosphate is precipitate and 1 molecule is formed.
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You are trying to determine the volume of the balloon needed to match the density of the air in the lab. You know that if you can get the balloon's density below this value, it will float. You measure both the temperature in the room as well as the mass of the balloon you will use and find they are 20.0°C and 0.570 grams, respectively. What volume of balloon will generate a density equal to that of the air around it? (Hint: Use the relationship you calculated above to determine the air density at the temperature given)
To solve this problem, we must be given first the density of air at 20 degrees Celsius. Looking up online, this is equal to:
density air (20C) = 0.0012041 g/mL
so that the volume is:
volume balloon = 0.57 g / (0.0012041 g/mL)
volume balloon = 473.38 mL
Which is the correct measure of density?
mass/volume
mass x volume
weight/volume
volume/weight
Option A= mass/volume
ExplanationDensity is a measurement that compares the amount of matter an object has to its volume. An object with much matter in a certain volume has high density. An object with little matter in the same amount of volume has a low density. Density is found by dividing the mass of an object by its volume.
The symbol most often used for density is ρ.
The formula for density is d = M/V, where d is density, M is mass, and V is volume.
The average density of human blood is 1.06 g/mL. What is the mass of blood in an adult with a blood volume of 5.5L? Express your answer in (a) grams & (b) ounces.
Answer : The mass of human blood in grams and ounce are 5830 grams and 205.647 ounce.
Explanation :
Density : It is defined as the mass contained per unit volume.
Formula used for density :
[tex]Density=\frac{Mass}{Volume}[/tex]
Given :
Density of human blood = 1.06 g/mL
Volume of human blood = 5.5 L = 5500 mL
conversion used : 1 L = 1000 mL
Now put all the given values in the above formula, we get the mass of human blood.
[tex]1.06g/mL=\frac{Mass}{5500mL}[/tex]
[tex]Mass=5830g[/tex]
The mass of human blood in grams = 5830 grams
Conversion used :
[tex]1\text{ ounce}=28.3495g\\\\1g=\frac{1}{28.3495}\text{ ounce}[/tex]
As, [tex]1g=\frac{1}{28.3495}\text{ ounce}[/tex]
So, [tex]5830g=\frac{5830g}{1g}\times \frac{1}{28.3495}\text{ ounce}=205.647\text{ ounce}[/tex]
Therefore, the mass of human blood in grams and ounce are 5830 grams and 205.647 ounce.
Predict what precipitate will form when a solution of barium chloride is mixed with a solution of potassium sulfate.
The chemical reaction between solution of barium chloride and potassium sulfate will form a precipitate of barium sulfate.
What is a chemical reaction?Chemical reactions are defined as reactions which occur when a substance combines with another substance to form a new substance.Alternatively, when a substance breaks down or decomposes to give new substances it is also considered to be a chemical reaction.
There are several characteristics of chemical reactions like change in color, change in state , change in odor and change in composition . During chemical reaction there is also formation of precipitate an insoluble mass of substance or even evolution of gases.
There are three types of chemical reactions:
1) inorganic reactions
2)organic reactions
3) biochemical reactions
During chemical reactions atoms are rearranged and changes are accompanied by an energy change as new substances are formed.
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Sediment spreads horizontality and it goes from youngest on top to oldest on bottom. When sediment deposits in water, it also spreads flat in all directions until it either runs out of material and pinches off or it hits a barrier. This is known as the _____.
A.law of original horizontality
B.law of superposition
C.law of original lateral continuity
D.law of gravity and oppositional force
E.law of cross-cutting relationships
Answer: It follows the law of original lateral continuity.
Explanation: Sediment is something that settle down in the liquid.
Law of Original Horizontality: This law states that the rocks and sediments are deposited horizontally.
Law of Superposition: This law states that the younger rocks are deposited or super imposed on the oldest rocks.
Law of Original Lateral Continuity: This law states that the sediment layers extent laterally or horizontally in all the direction as the younger rocks are added to the older rock which means that they are laterally continuous.
Law o Gravity and oppositional force: This law states that each particle attracts every other particle in the universe and is directly proportional to the product of the masses of two particles and inversely proportional to the square of the distance between them.
Law of cross-cutting relationship: This law states that fault which is cutting the rock is always younger than the rock.
From the above explained Law's, it is clear that the sediment follows Law of original lateral continuity.