Q: How many molecules of $$CO_2$$ are present in $$10.8 g of $$dry ice? (Molar mass of $$CO_2 = 44.01$ g/mol, N_A = 6.022$$ \times $$10^{23})$$

$$1.48 \times 10$$^{23}$$ molecules$

Question 1

Which of the following statements best explains why elements form compounds?

Accepted Answer

To lower the potential energy between the charged particles that compose atoms.

Question 2

What is the empirical formula of glucose, whose molecular formula is $$C_6H_{12}O_6$?

Accepted Answer

$$CH_2O$$

Question 3

A sample contains $$0.0265 g of $$carbon. How many moles of carbon are present? (Molar mass of C = $$12.01 g/$$mol)

Accepted Answer

$$2.21 	imes 10$$^{-3}$$ mol$

Question 4

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

Accepted Answer

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

Question 5

How many molecules of $$CO_2$$ are present in $$10.8 g of $$dry ice? (Molar mass of $$CO_2 = 44.01$ g/mol, N_A = 6.022$$ 	imes $$10^{23})$$

Accepted Answer

$$1.48 	imes 10$$^{23}$$ molecules$

Question 6

Which property is NOT typical of ionic compounds?

Accepted Answer

Malleability and ductility

Question 7

What is the mass percent of chlorine in $$CaCl_2$$? (Ca = $$40.08 g/$$mol, Cl = $$35.45 g/$$mol)

Accepted Answer

$$63.88\%$$

Question 8

Which of the following compounds contains both ionic and covalent bonds?

Accepted Answer

$$NH_4NO_3$$

Question 9

A pure silver ring contains $$2.80 	imes 10$$^{22}$$ silver atoms. How many grams of silver does it contain? (Ag = 107.87$ g/mol, N_A = 6.022$$ 	imes $$10^{23})$$

Accepted Answer

$$5.02 g$

Question 10

Which of the following best describes metallic bonding?

Accepted Answer

Valence electrons are pooled and delocalized among all metal atoms.

Question 11

What is the correct name for $$FeS$$?

Accepted Answer

Iron(II) sulfide

Question 12

Which of the following is the correct molecular formula for benzopyrene, given its empirical formula is $$C_5H_3$$ and its molar mass is $$252 g/$$mol? (C = $$12.01$$, H = $$1.01)$$

Accepted Answer

$$C_{20}H$$_{12}$$

Question 13

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

Accepted Answer

$$(NH_4$)_2SO_4$$

Question 14

Which of the following best describes why solid ionic compounds do NOT conduct electricity?

Accepted Answer

The ions are locked in place and cannot move.

Question 15

What is the mass of $$NaCl$$ that contains $$2.4 g of$$ $$Na if$$ $$NaCl is$$ $$39\%$$ $$Na by $$mass?

Accepted Answer

$$6.2 g$

Question 16

Which of the following is the correct name for $$SeO_2$$?

Accepted Answer

Selenium dioxide

Question 17

A compound is found to contain $$72.4\% Fe $$and $$27.6\% O by $$mass. What is the empirical formula? (Fe = $$55.85 g/$$mol, O = $$16.00 g/$$mol)

Accepted Answer

$$Fe_2O_3$$

Question 18

Which of the following is a property of molecular (covalent) compounds?

Accepted Answer

They are generally gases, liquids, or low-melting solids.

Question 19

Which of the following is the correct name for $$Mg(NO_3$)_2$$?

Accepted Answer

Magnesium nitrate

Question 20

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

Accepted Answer

Ionic bonds involve the transfer of electrons, while covalent bonds involve the sharing of electrons.

Molecules, Compounds, Chemical Formulas, and Bonding

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