to the nearest whole number what is the mass of one mole of hydrogen chloride

HESI A2

Chemistry Hesi A2

1. To the nearest whole number, what is the mass of one mole of hydrogen chloride?

A. 36 g/mol
B. 38 g/mol
C. 71 g/mol
D. 74 g/mol

Correct answer: C

Rationale: The molar mass of hydrogen chloride (HCl) is calculated by adding the atomic masses of hydrogen (H) and chlorine (Cl) together. The atomic mass of hydrogen is approximately 1 g/mol, and the atomic mass of chlorine is approximately 35.5 g/mol. Therefore, the molar mass of hydrogen chloride (HCl) is approximately 1 + 35.5 = 36.5 g/mol. When rounded to the nearest whole number, it is 36 g/mol. Therefore, the correct answer is 36 g/mol. Choices A, B, and D are incorrect as they do not reflect the accurate molar mass of hydrogen chloride.

2. What is the product of the decomposition of water?

A. Hydrogen and oxygen
B. Carbon dioxide
C. Nitrogen and hydrogen
D. Methane

Correct answer: A

Rationale: The correct answer is A: Hydrogen and oxygen. When water undergoes decomposition, it breaks down into hydrogen and oxygen gases through a process known as electrolysis. This reaction is represented by 2Hâ‚‚O â†’ 2Hâ‚‚ + Oâ‚‚. Choice B, carbon dioxide, is incorrect as it is not a product of water decomposition. Choice C, nitrogen and hydrogen, is incorrect as water decomposes into hydrogen and oxygen, not nitrogen. Choice D, methane, is incorrect as methane is not a product of water decomposition.

3. Which of the following elements is the most electronegative?

A. Oxygen
B. Fluorine
C. Nitrogen
D. Sodium

Correct answer: B

Rationale: Fluorine is the most electronegative element on the periodic table. It has the highest electronegativity value, indicating its strong ability to attract electrons in a chemical bond. This property makes it highly reactive, explaining why it is the correct answer in this question. Oxygen and Nitrogen are also electronegative elements, but they are not as electronegative as Fluorine. Sodium, on the other hand, is not electronegative; it is an electropositive element.

4. What is the energy required to remove the outermost electron from an atom called?

A. covalent bonding
B. electronegativity
C. atomic radius
D. ionization energy

Correct answer: D

Rationale: Ionization energy is the energy needed to remove the outermost electron from an atom, resulting in the formation of a positively charged ion. The higher the ionization energy, the more difficult it is to extract an electron. Electronegativity, however, measures an atom's ability to attract shared electrons in a chemical bond. Atomic radius refers to the distance from the nucleus to the outermost electron. Covalent bonding involves sharing electron pairs between atoms to create a stable bond. Therefore, the correct answer is ionization energy as it specifically relates to the energy needed to remove an electron from an atom.

5. Balance this equation: Zn + HCl â†’ ZnCl + H2.

A. Zn + 2HCl â†’ ZnCl + H2
B. Zn + HCl â†’ 2ZnCl + H2
C. 2Zn + 2HCl â†’ 2ZnCl + H2
D. Zn + 4HCl â†’ ZnCl + H2

Correct answer: C

Rationale: The given unbalanced equation is Zn + HCl â†’ ZnCl + H2. To balance it, we need to have equal atoms on both sides of the equation. The balanced equation is 2Zn + 2HCl â†’ 2ZnCl + H2. This balanced equation shows that two atoms of Zn combine with two molecules of HCl to form two molecules of ZnCl and one molecule of H2. Choice A is incorrect because it does not balance the equation. Choice B is incorrect as it does not have the same number of atoms on both sides. Choice D is incorrect because it does not balance the equation properly, resulting in an unequal number of atoms on both sides.