physical or chemical change. metal surface that becomes dull on exposure to air

Answer: 3808 ml

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.

Standard condition of temperature (STP)  is 273 K and atmospheric pressure is 1 atm respectively.  

To calculate the moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{4.03}{24}=0.17moles[/tex]

[tex]2Mg+O_2\rightarrow 2MgO[/tex]

2 moles of magnesium react with= [tex[2\times 22.4=44.8L[/tex] of oxygen at STP

Thus 0.17 moles of magnesium react with=[tex]\frac{44.8}{2}\times 0.17=3.8L=3808ml[/tex]

Thus the volume of oxygen required to react with 4.03 g of magnesium at STP is 3808 ml.

Chemical weathering and the formation of biochemical sediment remove carbon from the atmosphere by releasing carbon dioxide through the breakdown of rocks. This carbon dioxide can then be stored in the geosphere as biochemical sediments.

Chemical weathering and the formation of biochemical sediment play a crucial role in removing carbon from the atmosphere and storing it in the geosphere. Chemical weathering refers to the breakdown of rocks and minerals through chemical reactions, which releases carbon dioxide into the atmosphere. This carbon dioxide can then be dissolved in water and can react with other compounds to form biochemical sediments, such as calcium carbonate. These sediments eventually become part of the geosphere, storing carbon for long periods of time.

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The density of soft drink A is indeed 0.35 g/ml.

Given:

Mass of the soft drink (including sugar) = 110 g

The volume of the soft drink = 100 ml

Mass of sugar = 75 g

First, we need to find the mass of just the liquid (excluding the sugar), then we can calculate the density.

Mass of liquid = Total mass of soft drink - Mass of sugar

= 110  - 75

= 35 g

Now we can calculate the density:

Density = Mass ÷ Volume

Density = 35 ÷ 100

Density = 0.35 g/ml

The density of soft drink A is indeed 0.35 g/ml.

Final answer:

To calculate the amount of AlBr3 produced from 3.0 g of Al and 6.0 g of Br2, first, the limiting reactant is determined, which is Al. The theoretical yield of AlBr3 is 29.61 g, with no bromine remaining and some aluminum unreacted. For a 72% yield, 21.3192 g of AlBr3 would be collected.

Explanation:

To calculate the theoretical yield of AlBr3 produced from 3.0 g of aluminum (Al) and 6.0 g of bromine (Br2), first, we need to determine the limiting reactant. The balanced chemical equation for the reaction is:

2 Al + 3 Br2 → 2 AlBr3

Using molar masses (Al = 26.98 g/mol, Br2 = 159.808 g/mol), we calculate the moles of each reactant:

Al: 3.0 g / 26.98 g/mol = 0.111 moles

Br2: 6.0 g / 159.808 g/mol = 0.0375 moles

Based on the stoichiometry of the equation, 2 moles of Al react with 3 moles of Br2, making aluminum the limiting reactant.

The theoretical yield of AlBr3 can be calculated using the molar ratio from the balanced equation, from which 0.111 moles of Al would produce 0.111 moles of AlBr3. The molar mass of AlBr3 (266.693 g/mol) gives us a mass of 29.61 g.

No bromine would remain as all of it reacts, but some aluminum will remain unreacted.

For a 72% yield, the actual yield of AlBr3 = theoretical yield × percentage yield = 29.61 g × 0.72 = 21.3192 g.

The compound described is a fatty acid with a chain of 26 carbons, known as hexacosanoic acid, unless there are unsaturations not mentioned in the question.

Based on the information provided, the compound with a long chain of 26 carbons, a methyl group on one end, and an acid group on the other end, and without any nitrogen or sulfur atoms, can be regarded as a fatty acid. Fatty acids are carboxylic acids with long hydrocarbon chains. With 26 carbons, this compound can be considered a type of saturated or unsaturated fatty acid, depending on whether there are any double bonds in the hydrocarbon chain. The methyl group (CH3) indicates the end of the hydrocarbon chain, which is known in organic chemistry as the omega (ω) end. The acid group is the carboxylic acid functional group (COOH) at the other end of the molecule. Since the longest chain in this question is 26 carbons in length, with no double bonds mentioned, we might name it using the prefix for 26 carbons, which would be 'hexacos', followed by 'anoic acid' for the acid group, resulting in hexacosanoic acid. However, without more details on the nature of the hydrocarbon chain (specifically, its saturation), this nomenclature could change.

First we assume that the compound containing only C,H,and O is combusted completely in the presence of excess oxygen, so that the only things that can be produced are water and carbon dioxide.

From there we should back calculate the amount of Hydrogen that is in the original sample by taking all of the hydrogen in the 0.239g to came from the organic compound.

And since we know that the original mass of the sample was .100g, we can also easily get a mass % H by taking the mass Hydrogen calculated over the total original mass (.100 g)

So that:

0.239g H2O / (18.01 g/mol) = .01327 moles H20

.01327 Moles H20 * 2.02g H (per every mole H2O) = .0268g H initially present in the sample

.0268g H / .100g sample = 26.8% H by mass

The mass percent of hydrogen in the 0.1 g sample of compound containing carbon–hydrogen–oxygen is 26.6%

We'll begin by calculating the mass of the hydrogen in the compound. This can be obtained as follow:

Molar mass of H₂O = (2×1) + 16 = 18 g/mol

Molar mass of H₂ = 2 × 1 = 2 g/mol

Mass H₂O produced = 0.239 g

Mass of H = [tex]\frac{2}{18} * 0.239[/tex]

Finally, we shall determine the mass percent of Hydrogen in the compound. This can be obtained as follow:

Mass of H = 0.0266 g

Mass of compound = 0.1

[tex]Percentage = \frac{mass}{mass of compound} * 100\\\\= \frac{0.0266}{0.1} * 100[/tex]

Thus, the mass percent of hydrogen in the sample is 26.6%

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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.

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.

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.

Final answer:

The percent composition of Fe in the ferroaluminum alloy is approximately 33.82%.

Explanation:

To find the percent composition of the ferroaluminum, we need to determine the mass of iron and aluminum in the alloy. Based on the balanced chemical equations given, 1 mole of Fe is produced for every 2.07 g of the alloy, and 3 moles of H2 are produced for every 2.07 g of the alloy. From the molar mass of Fe (55.85 g/mol) and H2 (2.02 g/mol), we can calculate the mass of Fe and H2 produced. So, the percent composition of Fe in the alloy is:

mass of Fe / mass of ferroaluminum × 100%

= (0.70 g / 2.07 g) × 100%

= 33.82%

Therefore, the percent composition of Fe in the ferroaluminum is approximately 33.82%.

The reaction is limited by the amount of Lithium available. With the given amount of Lithium and Nitrogen gas, the maximum amount of Li3N that could be produced is 4.726 moles.

The question is looking for the maximum amount of Li3N that can be produced from given amounts of Li and N2. According to the chemical equation 6 Li + N2 → 2 Li3N, six moles of Li react with one mole of N2 to produce two moles of Li3N. Hence, the Li:N2:Li3N mole ratio is 6:1:2. If you have 14.18 moles of Li and 16.37 moles of N2, the reaction is limited by Li because it would require 16.37 moles of N2 to entirely consume 98.22 moles of Li (16.37 moles * 6). But since you only have 14.18 moles of Li, this will limit the formation of Li3N. Therefore, the maximum amount of Li3N that could be produced is 2/6 * 14.18 moles, which equals to 4.726 moles of Li3N.

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Zinc has a molar mass of about 65.38 g/mol. So we calculate the number of moles first:

moles Zinc = 8.93 g / (65.38 g/mol) = 0.1366 mol

We can calculate for the number of atoms using Avogadros number.

atoms Zinc = 0.1366 mol * 6.022 x 10^23 atoms / mol

atoms Zinc = 8.23 x 10^22 atoms

Iki also known as Lugol's solution, is an indicator used to test for the presence of starch. Benedict's reagent is used to test for the presence of reducing sugars, such as glucose and fructose

Lugol's solution is a yellow-brown solution that turns blue-black in the presence of starch.

Benedict's reagent is a clear blue solution that changes color to green, yellow, orange, or red, depending on the amount of reducing sugar present. Benedict's test is commonly used in the laboratory to detect the presence of reducing sugars in various substances.

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Final answer:

Ions are created when neutral atoms either lose or gain electrons, forming cations and anions, respectively. The periodic table helps predict the charges of ions depending on their group, where alkali metals form +1 cations, alkaline earth metals form +2 cations, and halogens form -1 anions. The formation of ionic compounds involves the combination of these oppositely charged ions to achieve electrical neutrality.

Explanation:

Ions are formed when atoms gain or lose electrons. When a neutral atom loses one or more electrons from its valence shell, it becomes a cation (a positive ion). Conversely, when it gains one or more electrons in its valence shell, it becomes an anion (a negative ion).

Charges of Ions and Ionic Compounds:

The periodic table can be a tool for predicting the charges of many ions based on their group. For instance, alkali metals form +1 ions, while alkaline earth metals form +2 ions. Halogens typically form -1 ions. Ionic compounds consist of these positive and negative ions in a ratio that balances their total charges, resulting in an electrically neutral compound.

Electron Configurations and Ion Charges:

It's important to note that ions only form through the movement of electrons, not protons. For elements within the same group on the periodic table, the number of valence electrons determines the common ion charge. Elements will either reach a stable electron configuration by losing or gaining electrons to form ions.

The interaction which is a direct result of chemical weathering is rust

forming on rocks.

Chemical weathering involves the interaction of rocks with chemical

substances such as minerals. In this process, the composition of the rocks

are usually changed.

Rusts forms on rocks during this process which hastens the breakdown of

rocks into tiny particles.

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