A quantity of 1.922 g of methanol (ch3oh) was burned in a constant-volume bomb calorimeter. consequently, the temperature rose by 5.14°c. if the heat capacity of the bomb plus water was 8.69 kj / °c, calculate the molar heat of combustion of methanol.

Answers

Answer 1

The molar heat of combustion of methanol is -745kJ/mol

Molar Heat of Combustion

This is heat released to the environment when one mole of a substance in this case methanol is completely burned.

Data given;

Mass of methanol = 1.922gChange in temperature = 5.14° CHeat capacity of the bomb calorimeter + water = 8.69kJ/°C

Number of moles

The number of moles of methanol is the ratio between the mass to the molar mass of methanol

mass = 1.922gmolar mass = 32g/mol

[tex]n=\frac{m}{M}\\n=\frac{1.922}{32}\\n=0.06moles[/tex]

The number of moles present in 1.922g of methanol is 0.06moles.

Heat of combustion

This is the heat required to completely burn a substance

[tex]Q=mc[/tex]ΔT

[tex]Q=8.69*5.14=44.67kJ[/tex]

Molar Heat of Combustion

ΔH = [tex]-(\frac{Q}{n})[/tex]

n = number of moles

ΔH = [tex]-\frac{44.7}{0.06}=-745kJ/mol[/tex]

The molar heat of combustion is -745kJ/mol

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Related Questions

If a sample of carbon monoxide is at 57 degreees celsius and under 67.88 kPa of pressure and takes up 85.3 L of space how many moles of carbon dioxide are present in the sample?

Answers

Final answer:

To determine the number of moles of carbon monoxide present in the sample, use the Ideal Gas Law equation.

Explanation:

To determine the number of moles of carbon monoxide present in the sample, we can use the Ideal Gas Law equation, which is PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.

First, convert the temperature from Celsius to Kelvin by adding 273.15. So, the temperature is 57°C + 273.15 = 330.15 K.

Now, rearrange the Ideal Gas Law equation to solve for n: n = PV / RT.

Substituting the given values into the equation, we have n = (67.88 kPa) * (85.3 L) / (0.0831 L·kPa/(mol·K)) * (330.15 K).

Simplifying the equation, we have n ≈ 231.36 moles of carbon monoxide in the sample.

What kind of chemist was Friedrich Wohler?

a. exochemist

b. analytical chemist

c. physical chemist

d. organic chemist

Answers

Friedrich Wohler was
d. organic chemist

Answer:

Friedrich Wöhler (German: [ˈvøːlɐ]) FRS(For) HFRSE (31 July 1800 – 23 September 1882) was a German chemist, known for his work in inorganic chemistry, being the first to isolate the chemical elements beryllium and yttrium in pure metallic form.

Died: 23 September 1882

Born: 31 July 1800, Eschersheim, Germany

Nationality: Germany

Explanation:

What nuclear symbol and hyphen notation for the isotope which has 26 protons and 30 neutrons?

Answers

Final answer:

The nuclear symbol for the isotope with 26 protons and 30 neutrons is 56 Fe, and the hyphen notation is iron-56 or Fe-56. The element is iron (Fe).

Explanation:

The isotope in question has 26 protons and 30 neutrons. To find the nuclear symbol and the hyphen notation, we need to identify the element and calculate the mass number. This notation represents that the atom is an iron isotope with a mass number of 56 and an atomic number of 26 .

The element with 26 protons is iron (Fe).

The mass number (A) is the sum of the protons and neutrons, so A = 26 + 30 = 56.

Therefore, the nuclear symbol is 56 Fe, where 56 is the mass number and Fe is the symbol for iron.

The hyphen notation for this isotope is iron-56 or Fe-56.

The molar mass of the compound was found to be 30.069 g/mol. what is the molecular formula? express your answer as a chemical formula.

Answers

For us to accurately determine what compound this is, additional info must be given. However I can suggest two compounds which have molecular mass of about 30.07 g/mol.

1. It could be NO or nitric oxide.

The molecular mass is 16 + 14= 30 g/mol

But if we search the exact weight, it is 30.01 g/mol

 

2. It could also be (CH3)2  or ethane.

The molecular mass is 2*12+ 6*1= 30 g/mol

But if we search the exact weight, it is 30.07 g/mol.

 

So we could say it more likely to to be (CH3)2 

Answer:

C2H6

Explanation:

There is no central carbon atom therefore you can put subscripts on both atoms.

It is said that hclo4 is a strong acid, whereas hclo2 is a weak acid. what does this mean in terms of the extent to which the two substances are ionized in solution?

Answers

a strong acid ionizes completely in aqueous solution just like Hclo4
HClO4(l) + H2O(l) ------>H3O+(aq) + ClO4-(aq)

but a weak doesn't ionize completely in water
HClO2 + H2O ⇌ H3O+ + ClO2-

The distinction between a strong acid (HClO₄) and a weak acid (HClO₂) lies in the extent of ionization in the solution. Strong acids ionize fully, while weak acids only partially ionize.

A strong acid is one that completely ionizes in water, while a weak acid only partially ionizes. The extent to which a substance is ionized in solution is determined by its dissociation constant (Ka).

HClO₄ is considered a strong acid because it fully dissociates into its ions when dissolved in water.

HClO₂ (chlorous acid),  is a weak acid. It only partially ionizes in water, meaning that only a fraction of the HClO₂ molecules dissociate into H+ and ClO⁻² ions. As a result, the concentration of H+ ions in the solution is lower compared to a strong acid like HClO₄, resulting in a weaker acidity.

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What are the periodic trends in atomic radius select all that are correct?

Answers

Actually we can see a lot of trends in the periodic table.

With regards to the atomic radius of the elements, going up to down there is an increasing pattern in the atomic radius.

While going left to right there is a decreasing pattern in the atomic radius.


Hence the smallest radius is on the upper right of the table.

Final answer:

Periodic trends in atomic radius indicate a decrease across a period due to increased nuclear charge pulling electrons closer, and an increase down a group due to the addition of electron shells. These trends result in the largest atoms being located in the lower left corner of the periodic table and the smallest in the upper right corner.

Explanation:

The question asks about the periodic trends in atomic radius. Atomic radius is a crucial concept in chemistry because it helps explain many properties of elements such as reactivity and bond length. Understanding these trends is fundamental for predicting and explaining chemical behavior.

Decrease Across a Period: Within a period, the atomic radius tends to decrease as the atomic number (Z) increases. This is because, across a period, electrons are added to the same energy level while the nucleus charges more positively, pulling electrons closer and resulting in a smaller atomic radius. For instance, going from potassium (K) to krypton (Kr), the radius decreases.

Increase Down a Group: Conversely, atomic radius increases as one moves down a group in the periodic table. This trend is due to the addition of electron shells as one moves to elements with higher atomic numbers, increasing the distance between the outer electrons and the nucleus. All alkali metals, for example, show an increase in atomic radius down the group.

In summary, atomic radii decrease from left to right across a row and increase from top to bottom down a column. Therefore, the largest atoms are found in the lower left corner of the periodic table, while the smallest are found in the upper right corner.

The concentration of calcium in a cell is 3%. the concentration of calcium in the surrounding fluid is 1%. how could the cell obtain more calcium?

Answers

The cell can obtain more calcium through Osmosis; which is a process whereby solvent molecules move through a permeable membrane from an area of of low concentration to an area of higher concentration.

How many atoms are in a single molecule of fe2o3?

Answers

One molecule of Fe2O3, iron (iii) oxide, or simply, rust, contains 2 atoms of Fe and 3 atoms of oxygen. Total of 5 atoms in a single molecule

Boron exists in two isotopes,boron-10 and boron-11. based on the atomic mass,which isotope should be more abundant

Answers

Answer:

The boron-11 should be more abundant

Explanation:

Atomic weight in the periodic table is an average value related to the percentaje of abundance of each isotope of the element.

Given that boron has only two isotopes (10 and 11), if their abundance would be 50%:

[tex]Ar=10*0.5+11*0.5=10.5[/tex]

If Ar<10.5, the boron 10 will be more abundantIf Ar>10.5 the boron 11 will be more abundant

Knowing that the boron's Ar is 10.81, we can afirm that boron-11 is more abundant.

Theoretically, boron atomicities of 10 and 11 are 10.5 on average. However, realistically speaking, boron has an atomic mass of 10.81 amu. Thus, it demonstrates that the average atomic mass of boron contains a higher abundance of boron-11. Atomic mass per unit, or amu, is a unit used to measure atomic mass.

If the abundance of boron-10 and boron-11 were equal, boron's atomic mass would be 10.5 amu. Therefore, the atomic mass of boron would be less than 10.5 amu if the percentage abundance of boron-10 is greater than the percentage abundance of boron-11.

In actuality, the atomic mass of boron is 10.81 amu rather than 10.5 amu, indicating that boron-11 has a higher proportion abundance than boron-10.

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When baking a cake and it appear to have ripples on its top what is the problem?

Answers

you might have too much gluten or the flour to liquid ratio is off

The metabolism of glucose produces co2(g) and h2o(l). how does the human body expel these reaction products?

Answers

CO2 and H2Ois released into the blood where there is a lower concentration of both outside of the cells that processed the glucose due to diffusion. Then the blood is transferred to the kidneys to be further processed then stored in the bladder to eventually out of the body by micturition. Sweat can also be used to rid the body of H2O. CO2 leaves the body through the lungs when exhalation is done.

How many periods does the modern periodic table have?

Answers

There are 7 periods in the modern periodic table

Determine whether the molecule ch3sh is polar.

Answers

ch3sh is polar because it has polar bonds & the net dipole is nonzero
Final answer:

To determine if a molecule is polar or nonpolar, follow these steps: draw the Lewis structure, figure out the molecular geometry, visualize or draw the geometry, and find the net dipole moment.

Explanation:

To determine if a molecule is polar or nonpolar, you need to follow a few steps:

Draw the Lewis structure of the molecule.Figure out the molecular geometry using VSEPR theory.Visualize or draw the geometry.Find the net dipole moment. If the net dipole moment is zero, the molecule is non-polar. If it is not zero, the molecule is polar.

In the case of CH3SH, the Lewis structure is H-C-H, with an S bonded to the central C atom. The geometry of the molecule is pyramidal, with the S atom at the top and the H atoms forming a triangular base. The S atom has higher electronegativity than the C and H atoms, so the S-H bond will be polar. Taking into account the molecular geometry, CH3SH is a polar molecule.

If an atom has 34 electrons, 46 neutrons, and 34 protons, what is its mass number? what is the name of the element?

Answers

mass number = protons + neutrons = 34+46 =80

the element with an atomic number of 34 and mass number of 80 is selenium

What is an atom called when the number of neutrons changes?

Answers

when neutron numbers are changed an ISOTOPE of the element is formed...

the atom becomes an ISOTOPE
Final answer:

When an atom's number of neutrons changes it becomes an isotope of the same element. Changes in the number of neutrons alter the atom's mass number but don't change the element type defined by the atomic number.

Explanation:

An atom becomes a different isotope of the same element when the number of neutrons changes. The atomic number which determines the type of the element doesn't change because it is defined by the number of protons. However, changing the number of neutrons alters the mass number. For example, hydrogen typically has no neutrons,but if a neutron is added, it becomes Deuterium, an isotope of hydrogen. Another example can be seen in Carbon which usually has 6 neutrons in its most common form (Carbon-12), but if we add an extra neutron it becomes Carbon-13, another isotope. These isotopes, while having the same number of protons and electrons, thus exhibiting the same chemical properties have different physical properties.

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If a potassium atom has an atomic number of 19 and a mass number of 39, how many protons, electrons, and neutrons are in the atom?

Answers

Answer: The Atom would have:  

9 protons

19 electrons (since atoms are electrically neutral and have the same number of electrons as protons)

20 neutrons

Explanation: Hope this Helps.

The following statement is a(n) _____.

There is a significant difference between how elderly people and young people feel about politics.

hypothesis
opinion
scientific law
problem

Answers

hypothesis hope thats the awnser

Answer:

Opinion

Explanation:

This is an opinion, actually. A Hypothesis has an "if/then" statement, for example, "IF I do not tie a knot at the end of a balloon THEN it will deflate". A scientific law states a fact that can be proven, such as Newtons Laws. A problem is the question you ask without making an educated guess.

Hope I helped! :)

Which element has three unpaired electrons in its p orbital? carbon (atomic number 6) oxygen (atomic number 8) nitrogen (atomic number 7) beryllium (atomic number 4)

Answers

The element has three unpaired electrons in its p orbital is nitrogen (atomic number 7). 

Answer: The correct answer is Nitrogen.

Explanation:

Electronic configuration is the representation which helps in determination of the total number of electrons and valence electrons that are present in an element.

For the given options:

Option 1: Carbon having atomic number 6

Electronic configuration of C = [tex]1s^22s^22p^2[/tex]

It has 2 electrons in its p-orbital.

Option 2: Oxygen having atomic number 8

Electronic configuration of O = [tex]1s^22s^22p^4[/tex]

It has 4 electrons in its p-orbital.

Option 3: Nitrogen having atomic number 7

Electronic configuration of N = [tex]1s^22s^22p^3[/tex]

It has 3 electrons in its p-orbital.

Option 4: Beryllium having atomic number 4

Electronic configuration of Be = [tex]1s^22s^2[/tex]

It has 0 electrons in its p-orbital.

From the above information, the correct answer is Nitrogen.

if a match were placed in the cone close to the barrel of the gas burner will it ignite

Answers

i think it would seeing as you typicaly have to use a match to light a gas burner

Where do the protons and electrons come from that are used in the electron transport chain?

Answers

The energy generated by the movement of electrons is used to pump electrons across the inner mitochondrial membrane to an area of higher concentration. 17. Where do these protons (H+) come from? The originally came from a glucose molecule and were carried to the electron transport chain by NADH and FADH2.

The answer would be glucose molecule.

What conditions increase the rate of weathering erosion and mass wasting?

Answers

Temperature and moisture are two of the most influential factors on erosion. As temperatures and moisture levels increase, it becomes much more favorable for rock erosion. Rock characteristics can also be linked to erosion: the harder the rock, the less likely it will be to weather and erode.

Suppose you conduct an experiment to determine how temperature affects the amount of salt which can be dissolved in 100 ml of water. what is the independent variable?

Answers

The independent variable is the part of the system which is changed to determine the effect on the outcome. In this case, temperature is the independent variable.

The amount of dissolved salt depends upon the temperature, so it would be the dependent variable.

A fruit drink concentrate is 15% water. how many liters of pure water should be added to 12l of concentrates to produce a mixture that is 50% water

Answers

1 liter of drink contain water = 15% 12l of drink contain water = 15 % 12l of drink contain water at 15% = 1.8l 12l of drink contain water at 50% = 6l Water to add in 15% water drink = 6l – 1.8l = 4.2l After adding 4.2l of water in 12l 15% water drink, we get 50% water drink.

A sample of aluminum metal absorbs 10.3 j of heat, upon which the temperature of the sample increases from 23.2 °c to 30.5 °c. since the specific heat capacity of aluminum is 0.90 j/g-k, the mass of the sample is ________ g.

Answers

1.6 g First, calculate the change in temperature. 30.5 - 23.2 = 7.3 K Now we have 3 pieces of data, the units involved are K, J/(g K), and J. We wish to create a result with the units being g. Let's start with the specific heat. 0.90 J/(g K) Now let's cancel out the K by multiplying by our data with K 0.90 J/(g K) * 7.3 K = 6.57 J/g Now we want to cancel out the J and get g on top. We can do that by dividing the J value we have by the calculated value above. So 10.3 J / 6.57 J/g = 1.567732116 g Rounding to 2 significant figures gives us a mass of 1.6 g Remember, for most problems, simply look at the units you have and what you desire for the units in the final result. By paying attention to this, the math operations you need are pretty automatic.

Pure quartz and the gemstone amethyst are nearly alike chemically. what physical property would be used to tell them apart

Answers

Pure quartz and gemstone amethyst are different varieties of quartz. Quartz is a chemical compound made up of silicon and oxygen. As both pure quartz and gemstone amethyst are quartz, these have the same chemical properties.

Pure quartz is also known as rock crystal or clear crystal. It is transparent and colorless. Gemstone quartz is a quartz of purple color. Thus the physical property that differentiates a pure quartz from amethyst is the color of the compound.

What is the value of the bond angles in sih4?

Answers

109.5°.
       
VESPR helps predict the bond angles with the electrons being the most out. By looking that the structure of the molecule, one Si and four H, the Si atom can be seen as the center and the four H atoms can be seen around it. Now think about how the H atoms would be placed, ideally they would be placed the farthest distance from each other equidistant. So in this case it would be 109.5°.

Why does an ionic compound conduct an electric current when the compound is melted but not when it is in the solid state?

Answers

There are two types of compound, covalent compound and ionic compound in chemistry, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. Due to ease in movement of ions, melted ionic compound conduct electricity.

What is chemical Compound?

Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.

Ionic compound are very hard. They have high melting and boiling point because of strong ion bond. When ionic compounds are in solid state the charged particles (ions) are not free to move but when in melted for, the ions are free to move. So, now they can conduct electricity.

Due to ease in movement of ions, melted ionic compound conduct electricity.

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An unknown substance is made only of identical atoms that cannot be broken down. this substance is a ________.mixtureelementcompound

Answers

The substance is a element.

Use lewis theory to determine the formula for the compound that forms from ca and s.

Answers

The formula in terms of the oxidation numbers for the elements. The sum of the oxidation numbers for a compound must be zero. Ca3N2 KBr Cs2S CsF

A cone with a mass of 6 g has a radius measuring 5 cm and a height of 2 cm. What is its density?

Answers

calculate the volume of the cylinder by the given measurements (5cm and 2 cm) then 6g (mass) ÷ volume of cylinder≈ density

Answer: The density of cone is [tex]0.115g/cm^3[/tex]

Explanation:

The equation used to calculate the volume of cone is:

[tex]V=\frac{1}{3}\pi r^2h[/tex]

where,

V = volume of cone

r = radius of the cone = 5 cm

h = height of the cone = 2 cm

Putting values in above equation, we get:

[tex]V=\frac{1}{3}\times (3.14)\times (5)^2\times 2\\\\V=52.33cm^3[/tex]

To calculate volume of a substance, we use the equation:

[tex]\text{Density of a substance}=\frac{\text{Mass of a substance}}{\text{Volume of a substance}}[/tex]

We are given:

Mass of cone = 6 g

Volume of cone = [tex]52.33cm^3[/tex]

Putting values in above equation, we get:

[tex]\text{Density of cone}=\frac{6g}{52.33cm^3}\\\\\text{Density of cone}=0.115g/cm^3[/tex]

Hence, the density of cone is [tex]0.115g/cm^3[/tex]

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