Q: Which of the following best describes a mole in chemistry?

A unit that contains $$6.02 \times 10$$^{23}$$ particles of a substance.

Q: How many molecules are in $$3.0$$ moles of sodium fluoride ($$NaF$$)?

$$1.8 \times 10$$^{24}$$ molecules

Q: Which of the following is NOT a correct conversion factor for Avogadro’s number?

$$1 \text{ g} / 6.02 \times 10$$^{23}$$ \text{ atoms}$$

Question 1

Which of the following best describes a mole in chemistry?

Accepted Answer

A unit that contains $$6.02 	imes 10$$^{23}$$ particles of a substance.

Question 2

A sample contains $$1.204 	imes 10$$^{24}$$ atoms of silver (Ag). How many moles of silver are present?

Accepted Answer

$$2.00$$ moles

Question 3

What is the chemical formula for a compound formed between an unknown metal X and fluorine, given the formula is $$XF_3$$? In which group is X most likely found?

Accepted Answer

Group 3A

Question 4

How many hydrogen atoms are present in one formula unit of $$(NH_4$)_2SO_4$$?

Accepted Answer

8

Question 5

Calculate the molar mass of $$CaCl_2$$ using the atomic weights: Ca = $$40.08$$ amu, Cl = $$35.45$$ amu.

Accepted Answer

$$110.98 g/$$mol

Question 6

Which of the following is the correct molar mass for ammonium chloride ($$NH_4Cl$$)?

Accepted Answer

$$53.50 g/$$mol

Question 7

How many molecules are in $$3.0$$ moles of sodium fluoride ($$NaF$$)?

Accepted Answer

$$1.8 	imes 10$$^{24}$$ molecules

Question 8

Which of the following best describes the relationship between formula mass and molar mass?

Accepted Answer

Formula mass and molar mass have the same numerical value but different units.

Question 9

If you have $$2.11 	imes 10$$^{24}$$ atoms of H_2$, how many moles do you have?

Accepted Answer

$$3.50$$ mol

Question 10

Which of the following is the correct formula for dihydrogen sulfide?

Accepted Answer

$$H_2S$$

Question 11

A box of donuts contains 12 donuts. This is an example of which type of counting unit in chemistry?

Accepted Answer

Dozen

Question 12

Which of the following is NOT a correct conversion factor for Avogadro’s number?

Accepted Answer

$$1 	ext{ g} / 6.02 	imes 10$$^{23}$$ 	ext{ atoms}$$

Question 13

Which of the following best explains why the molar mass of $$H_2O is$$ $$18.02 g/$$mol?

Accepted Answer

It is the sum of the atomic masses of 2 H atoms and 1 O atom.

Question 14

Which of the following compounds contains the greatest number of oxygen atoms per formula unit?

Accepted Answer

$$Al_2$$($$CO_3)_3$

Question 15

A student calculates the formula mass of $$MgSO_4 as $$follows: $$1 	imes 24.31$$ amu (Mg) $$+ 1 	imes 32.06$$ amu (S) $$+ 4 	imes 16.00$$ amu (O). What is the correct formula mass?

Accepted Answer

$$120.37$$ amu

Question 16

Which of the following best describes the difference between an ionic and a molecular compound?

Accepted Answer

Ionic compounds are formed from metals and nonmetals; molecular compounds are formed from nonmetals only.

Question 17

Which of the following is the correct molar mass for ethanol ($$C_2H_5OH$$)?

Accepted Answer

$$46.08 g/$$mol

Question 18

If you have $$7.0$$ moles of sulfur (S), how many atoms do you have?

Accepted Answer

$$4.2 	imes 10$$^{24}$$ atoms

Question 19

Which of the following is the correct chemical formula for a compound containing two ammonium ions and one sulfate ion?

Accepted Answer

$$(NH_4$)_2SO_4$$

Chemical Quantities, The Mole, and Molar Mass – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard