Q: What is the mass percent of oxygen in H$$_2O$$?

$$\frac{16.00}{18.02} \times 100\% = 88.8\%$$

Q: A sample of magnesium nitrate, Mg(NO$$_3$$)$$_2$$, has a mass of 128.5 g. How many grams of nitrogen are present in the sample? (Mg = 24.31, N = 14.01, O = 16.00)

$$\frac{2 \times 14.01}{148.33} \times 128.5 = 24.2 g$$

Q: What is the formula mass of calcium phosphate, Ca$$_3(PO$_4$$)$$_2$$? (Ca = 40.08, P = 30.97, O = 16.00)

$$3 \times 40.08 + 2 \times (30.97 + 4 \times 16.00) = 310.18 g/$$mol

Q: A 10.0 g sample of CaCl$$_2$$ contains how many grams of chlorine? (Ca = 40.08, Cl = 35.45)

$$\frac{2 \times 35.45}{110.98} \times 10.0 = 6.39 g$$

Question 1

Which of the following compounds is an example of a molecular (covalent) compound?

Accepted Answer

CO$$_2$$

Question 2

Which of the following is the correct formula for ammonium sulfate?

Accepted Answer

(NH$$_4$$)$$_2SO$_4$$

Question 3

What is the mass percent of oxygen in H$$_2O$$?

Accepted Answer

$$\frac{16.00}{18.02} 	imes 100\% = 88.8\%$$

Question 4

Which of the following is the correct name for Fe$$_2(SO$_4$$)$$_3$$?

Accepted Answer

Iron(III) sulfate

Question 5

Which of the following is an empirical formula?

Accepted Answer

CH$$_2O$$

Question 6

A sample of magnesium nitrate, Mg(NO$$_3$$)$$_2$$, has a mass of 128.5 g. How many grams of nitrogen are present in the sample? (Mg = 24.31, N = 14.01, O = 16.00)

Accepted Answer

$$\frac{2 	imes 14.01}{148.33} 	imes 128.5 = 24.2 g$$

Question 7

Which of the following is the correct formula for dinitrogen pentoxide?

Accepted Answer

N$$_2O$_5$$

Question 8

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons; covalent bonds involve the sharing of electrons.

Question 9

What is the formula mass of calcium phosphate, Ca$$_3(PO$_4$$)$$_2$$? (Ca = 40.08, P = 30.97, O = 16.00)

Accepted Answer

$$3 	imes 40.08 + 2 	imes (30.97 + 4 	imes 16.00) = 310.18 g/$$mol

Question 10

Which of the following is the correct name for H$$_2SO$_3$$?

Accepted Answer

Sulfurous acid

Question 11

Which of the following is the correct formula for the polyatomic ion phosphate?

Accepted Answer

PO$$_4$$^{3-}$$

Question 12

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is its empirical formula?

Accepted Answer

CH$$_2O$$

Question 13

Which of the following is the correct name for Na$$_2CO$_3$$·10H$$_2O$$?

Accepted Answer

Sodium carbonate decahydrate

Question 14

Which of the following is the correct structural formula for ethanol?

Accepted Answer

CH$$_3CH$_2OH$$

Question 15

How many moles of oxygen atoms are present in 1 mole of Al$$_2(SO$_4$$)$$_3$$?

Accepted Answer

12

Question 16

Which of the following is the correct name for P$$_2O$_5$$?

Accepted Answer

Diphosphorus pentoxide

Question 17

A 10.0 g sample of CaCl$$_2$$ contains how many grams of chlorine? (Ca = 40.08, Cl = 35.45)

Accepted Answer

$$\frac{2 	imes 35.45}{110.98} 	imes 10.0 = 6.39 g$$

Question 18

Which of the following is the correct name for HNO$$_3$$?

Accepted Answer

Nitric acid

Question 19

Which of the following is the correct formula for the polyatomic ion sulfate?

Accepted Answer

SO$$_4$$^{2-}$$

Question 20

Which of the following is the correct name for K$$_2Cr$_2O$_7$$?

Accepted Answer

Potassium dichromate

General Chemistry: Naming, Formulas, and Mass Calculations Study Guide

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