Question 1

Which of the following best describes the shape of the ammonia (NH$$_3) $$molecule according to its Lewis structure and VSEPR theory?

Accepted Answer

Trigonal pyramidal

Question 2

How many valence electrons are present in the sulfate ion (SO$$_4$$^{2-}$$)?

Accepted Answer

32

Question 3

Which of the following is the correct balanced chemical equation for the combustion of methane (CH$$_4) in $$oxygen?

Accepted Answer

$$\mathrm{CH_4$ + 2O_2 \rightarrow CO_2$ + 2H_2O}$$

Question 4

Given the Lewis structure for carbon dioxide (CO$$_2$$), what is its molecular shape?

Accepted Answer

Linear

Question 5

Which of the following is a correct balanced equation for the decomposition of hydrogen peroxide (H$$_2O$_2$$)?

Accepted Answer

$$\mathrm{2H_2O_2 \rightarrow 2H_2O + O_2$}$$

Question 6

A student determines the molar mass of an unknown compound by measuring 0.500 g of the compound and finding it produces 0.250 mol of gas at STP. What is the molar mass of the compound?

Accepted Answer

$$2.00\ \mathrm{g/mol}$$

Question 7

Which of the following is a single displacement reaction?

Accepted Answer

$$\mathrm{Zn + 2HCl \rightarrow $$ZnCl_2$$ + H_2$}$$

Question 8

What is the total number of valence electrons in the nitrate ion (NO$$_3^-$$)?

Accepted Answer

24

Question 9

Which of the following word equations represents a combination reaction?

Accepted Answer

Hydrogen gas reacts with oxygen gas to form water.

Question 10

Which of the following is the correct Lewis structure description and shape for water (H$$_2O$$)?

Accepted Answer

Two single bonds, two lone pairs on oxygen; bent shape

Question 11

A student mixes copper(II) sulfate solution with iron metal. Which type of reaction occurs and what is the balanced equation?

Accepted Answer

Single displacement; $$\mathrm{Fe + $$CuSO_4$$ \rightarrow $$FeSO_4$$ + Cu}$$

Question 12

Which of the following is the correct balanced equation for the decomposition of calcium carbonate (CaCO$$_3$$)?

Accepted Answer

$$\mathrm{$$CaCO_3$$ \rightarrow CaO + CO_2$}$$

Question 13

Which molecule has a tetrahedral shape according to its Lewis structure and VSEPR theory?

Accepted Answer

Methane (CH$$_4)$$

Question 14

A student is given 1.00 g of an unknown gas and collects 0.025 mol at STP. What is the molar mass of the gas?

Accepted Answer

$$40.0\ \mathrm{g/mol}$$

Question 15

Which of the following is the correct balanced equation for the combination reaction between sodium and chlorine gas?

Accepted Answer

$$\mathrm{2Na + Cl_2$ \rightarrow 2NaCl}$$

Question 16

Which of the following molecules has a trigonal planar shape?

Accepted Answer

Boron trifluoride (BF$$_3)$$

Question 17

Which of the following is a correct single displacement reaction?

Accepted Answer

$$\mathrm{Mg + 2HCl \rightarrow $$MgCl_2$$ + H_2$}$$

Question 18

How many valence electrons are present in the phosphate ion (PO$$_4$$^{3-}$$)?

Accepted Answer

35

Question 19

Which of the following is the correct balanced equation for the combustion of propane (C$$_3H$_8$$)?

Accepted Answer

$$\mathrm{C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O}$$

Lab Exam 2 Study Guide: Chemical Reactions, Lewis Structures, and Molar Mass Determination

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