Question

use with textbook pages 202 - 211.
chemical equations
match the term on the left with the best descriptor on the right. each descriptor may be used only once.

1. product
2. reactant
3. coeffcient
4. word equation
5. skeleton equation
6. chemical reaction
7. chemical equation

a. a chemical that reacts in a chemical reaction
b. a chemical that forms in a chemical reaction
c. a chemical change in which new substances are formed
d. a chemical equation that is written using chemical names
e. an integer placed in front of a formula in a chemical equation
f. a chemical equation that is written using chemical formulas
g. a set of chemical formulas that identify the reactants and products in a chemical reaction

1. which of following describes the law of conservation of mass?

i the mass is conserved in a chemical reaction
ii the total mass of the products is equal to the total mass of the reactants in a chemical reaction.
iii. the total number of each kind of atom at the start of the reaction is equal to the total number of each kind of atom after the reaction.
a. i and ii only
b. i and iii only
c. ii and iii only
d. i, ii, and iii

1. how many oxygen atoms are there in the compound lead(iv) bisulphate, pb(hso₄)₂?

a. 2
c. 8
b. 4
d. 16

1. which of the following are diatomic elements?

i iodine
ii nitrogen
iii hydrogen
a. i and ii only
c. ii and iii only
b. i and iii only
d. i, ii, and iii
use the following unbalanced equation to answer question 11.
pcl₅ + h₂o → hcl + h₃po₄

1. which of the following sets of coefficients will balance the equation?

a. 1, 4, 5, 1
c. 1, 3, 5, 2
b. 1, 5, 4, 1
d. 1, 4, 2, 1

1. a solution of sodium sulphide is mixed with a solution of copper(ii) nitrate. a precipitate of copper sulphide is formed in a solution of sodium nitrate. what are the reactants in this chemical reaction?

a. na₂s and cus
b. cus and nano₃
c. na₂s and cu(no₃)₂
d. na₂so₄ and cu₂no₃

1. a piece of aluminum metal is placed in a solution of sulphuric acid, h₂so₄. a compound, aluminum sulphate, forms and bubbles are seen going to the surface. what type of gas formed during this reaction?

a. oxygen
c. carbon dioxide
b. hydrogen
d. carbon monoxide

Explanation:

Step1: Analyze question 9

In \(Pb(HSO_{4})_{4}\), for each \(HSO_{4}^{-}\) ion, there are 4 oxygen atoms. Since there are 4 \(HSO_{4}^{-}\) ions (due to the sub - script 4 outside the parentheses), the total number of oxygen atoms is \(4\times4 = 16\).

Step2: Analyze question 10

Diatomic elements are elements that exist as two - atom molecules in their elemental form. Iodine (\(I_{2}\)), nitrogen (\(N_{2}\)), and hydrogen (\(H_{2}\)) are diatomic elements.

Step3: Analyze question 11

For the equation \(PCl_{5}+H_{2}O
ightarrow HCl + H_{3}PO_{4}\), we use the method of balancing atoms.

• Balance P: There is 1 P on the left and 1 P on the right.
• Balance Cl: There are 5 Cl on the left. So, we put a 5 in front of \(HCl\) on the right.
• Balance O: Let the coefficient of \(H_{2}O\) be \(x\). After balancing Cl (\(PCl_{5}+xH_{2}O

ightarrow5HCl + H_{3}PO_{4}\)), for O atoms: \(x = 4\) (because there are 4 O atoms in \(H_{3}PO_{4}\)). The balanced equation is \(PCl_{5}+4H_{2}O = 5HCl+H_{3}PO_{4}\), so the coefficients are \(1,4,5,1\).

Step4: Analyze question 12

The reactants are the substances that undergo a chemical change. The reaction is \(Na_{2}S+Cu(NO_{3})_{2}
ightarrow CuS + 2NaNO_{3}\). The reactants are \(Na_{2}S\) (sodium sulphide) and \(Cu(NO_{3})_{2}\) (copper (II) nitrate).

Step5: Analyze question 13

The reaction of aluminum (\(Al\)) with sulphuric acid (\(H_{2}SO_{4}\)) is \(2Al + 3H_{2}SO_{4}=Al_{2}(SO_{4})_{3}+3H_{2}\uparrow\). The gas formed is hydrogen.

Answer:

1. D. 16
2. D. I, II, and III
3. A. 1, 4, 5, 1
4. C. \(Na_{2}S\) and \(Cu(NO_{3})_{2}\)
5. B. hydrogen