Q: What is the formula mass of $$\mathrm{$$MgCl_2$$}$$? (Atomic masses: Mg = 24.31 amu, Cl = 35.45 amu)

$$24.31 + 2 \times 35.45 = 95.21$$ amu

Question 1

Which statement best explains why the properties of sodium chloride (table salt) are different from those of its constituent elements, sodium and chlorine?

Accepted Answer

Sodium chloride is a compound, and compounds have properties distinct from the elements that compose them.

Question 2

According to the law of constant composition, what is true for all samples of pure water?

Accepted Answer

They contain hydrogen and oxygen in a fixed mass ratio of 8:1.

Question 3

Which of the following is the correct chemical formula for a compound formed between magnesium and chlorine?

Accepted Answer

$$\mathrm{$$MgCl_2$$}$$

Question 4

How many oxygen atoms are present in one formula unit of $$\mathrm{Mg(NO_3$)_2}$$?

Accepted Answer

6

Question 5

Which of the following best describes the difference between a compound and a mixture?

Accepted Answer

A compound contains elements in fixed, definite proportions, while a mixture contains elements in variable proportions.

Question 6

What is the empirical formula for glucose, $$\mathrm{C_6H_{12}O_6$}$$?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 7

Which of the following is a molecular element?

Accepted Answer

Chlorine ($$\mathrm{Cl_2$})$$

Question 8

Which of the following compounds is an ionic compound?

Accepted Answer

$$\mathrm{NaCl}$$

Question 9

What is the correct name for $$\mathrm{$$FeCl_3$$}$$?

Accepted Answer

Iron(III) chloride

Question 10

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

Accepted Answer

$$\mathrm{(NH_4$)_2SO_4}$$

Question 11

What is the formula mass of $$\mathrm{$$MgCl_2$$}$$? (Atomic masses: Mg = 24.31 amu, Cl = 35.45 amu)

Accepted Answer

$$24.31 + 2 	imes 35.45 = 95.21$$ amu

Question 12

Which of the following is the correct name for $$\mathrm{$$KNO_3$$}$$?

Accepted Answer

Potassium nitrate

Question 13

Which of the following acids is correctly named?

Accepted Answer

$$\mathrm{$$HNO_2$$}$$: nitrous acid

Question 14

What is the correct name for $$\mathrm{N_2O_5}$$?

Accepted Answer

Dinitrogen pentoxide

Question 15

Which of the following is a polyatomic ion found in household bleach?

Accepted Answer

Hypochlorite ($$\mathrm{ClO^-})$$

Question 16

Which of the following best describes the difference between the molecular formula and the empirical formula?

Accepted Answer

The empirical formula shows the simplest whole-number ratio of atoms, while the molecular formula shows the actual number of atoms.

Question 17

Which of the following is the correct name for $$\mathrm{H_2SO_3} (aq$$)?

Accepted Answer

Sulfurous acid

Question 18

A sample of ammonia ($$\mathrm{NH_3$}) is $$decomposed and found to contain 14.0 g of nitrogen and 3.0 g of hydrogen. What is the nitrogen-to-hydrogen mass ratio in ammonia?

Accepted Answer

$$4.7:1$$

Question 19

Which of the following is the correct formula for calcium nitrate?

Accepted Answer

$$\mathrm{Ca(NO_3$)_2}$$

Question 20

Which of the following is the correct name for $$\mathrm{$$CuSO_4$$}$$?

Accepted Answer

Copper(II) sulfate

Chapter 5: Molecules and Compounds – Structured Study Notes

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