Chemical Reactions

Question 1

Balance the following chemical equation:

CH4 + Cl2 → CCl4 + HCl

CH4 + 4 Cl2 → CCl4 + 4 HCl
CH4 + Cl2 → CCl4 + HCl
2 CH4 + Cl2 → 2 CCl4 + HCl
2 CH4 + 2 Cl2 → 2 CCl4 + 2 HCl

Answer 1

CH4 + 4Cl2 → CCl4 + 4HCl

Extra:
CH4 + Cl2 → CCl4 + HCl

C: 1 C: 1
H: 4 H: 1
Cl: 2 Cl: 5

CH4 + Cl2 → CCl4 + 4 HCl
C: 1 C: 1
H: 4 H: 4
Cl: 2 Cl: 8

CH4 + 4 Cl2 → CCl4 + 4 HCl
C: 1 C: 1
H: 4 H: 4
Cl: 8 Cl: 8

Question 2

Which type of chemical reaction is demonstrated by the reaction below?

Ba(NO3)2 + Na2SO4 → BaSO4 + 2 NaNO3

Double replacement
Single replacement reaction
Acid-base reaction
Decomposition

Answer 2

Double replacement

Extra:

In a double replacement reaction, two metal ions (Ba²+ and Na+) switch places with each other in two ionic compounds.

A similar reaction is the single replacement reaction, where two metal ions are swapped in only a single ionic compound.

In a decomposition reaction, a single compound is broken down into several other smaller compounds.

In an acid-base reaction, a proton (H+) is transferred from one molecule to another, which has not occurred in the reaction above.

Question 3

Which of the following compounds contains ionic bonds?

C6H6
O2
NaBr
CH4

Answer 3

NaBr

Ionic bonds form when elements from opposite sides of the periodic table form an ionic compound. In the question above, Na is a metal from the left side of the periodic table, and Br is a nonmetal from the right side of the periodic table.

Question 4

In a redox reaction, oxidation is the _______ of electrons and reduction is the _______ of electrons.

gain, gain
gain, loss
loss, gain
loss, loss

Answer 4

loss, gain

Extra:

In a redox reaction, oxidation is the loss of electrons, and reduction is the gain of electrons.

A good way to remember this is OIL RIG:

Oxidation Is Loss Reduction Is Gain

Question 5

Which of these statements is true about pH?

Blood has an acidic pH
Adding an acid to a solution will increase the pH
Higher pH values indicate a higher [H+]
A pH of 6 is more acidic than a pH of 8

Answer 5

A pH of 6 is more acidic than a pH of 8

Lower pH values indicate a more acidic solution

Question 6

The same single-replacement reaction is run in two different beakers. The beakers are labeled as Beaker A and B and are heated to 75oC and 100oC, respectively. If the reactions are run for 15 minutes each, which of the following results would you expect to observe?

Beaker A produces more product than Beaker B
No products are produced in either beaker
The two beakers produce the same amount of product
Beaker B produces more product than Beaker A

Answer 6

Beaker B produces more product than Beaker A

Question 7

Balance the following chemical equation:

C3H8 + O2 → CO2 + H2O

2 C3H8 + O2 → 6 CO2 + H2O
2 C3H8 + O2 → CO2 + H2O
C3H8 + 5 O2 → 3 CO2 + 2 H2O
C3H8 + 5 O2 → 3 CO2 + 4 H2O

Answer 7

C3H8 + 5 O2 → 3 CO2 + 4 H2O

Extra:
C3H8 + O2 → CO2 + H2O
C: 3    C: 1
H: 8    H: 2
O: 2    O: 3

C3H8 + O2 → 3 CO2 + H2O
C: 3 C: 3
H: 8 H: 2
O: 2 O: 7

C3H8 + O2 → 3 CO2 + 4 H2O
C: 3 C: 3
H: 8 H: 8
O: 2 O: 10

C3H8 + 5 O2 → 3 CO2 + 4 H2O
C: 3 C: 3
H: 8 H: 8
O: 10 O: 10

Question 8

Br2 is classified as which of the following?

Molecule
Ion
Atom
Compound

Answer 8

Molecule

Question 9

Predict the missing product of the following reaction:

Zn + AgNO3 → Ag + _________

Zinc nitrate
Zinc oxide
Zinc nitrite
Silver nitrate

Answer 9

Zinc nitrate

Extra:
Nitrate = no3
nitrite = no2

Question 10

Correctly identify X in the reaction below:

210⁄84 Po → X + 4⁄2 He

218/84 At
214/86 He
214/86 Pb
206/82 Pb

Answer 10

206⁄82 Pb

Question 11

How many moles of O2 will be produced when the reaction below is properly balanced?

H2O2 → H2O + O2

2 moles
1 mole
4 moles
3 moles

Answer 11

1 mole

Question 12

Which of the following is an example of a redox reaction?

Synthesis
Single replacement reaction
Acid-base neutralization
Combustion

Answer 12

Combustion

Question 13

Identify the acid in the following reaction:

CH3COOH + NaOH → NaOOCCH3 + H2O

H2O
NaOOCCH3
CH3COOH
NaOH

Answer 13

CH3COOH

Question 14

Which of the following are produced from the reaction between a Brønsted-Lowry acid-base pair?

A weak acid and base
Water and a strong base
A strong acid and weak base
A salt and water

Answer 14

A salt and water

Question 15

Which of the following scenarios will increase the likelihood of reactant molecules colliding with one another during a liquid chemical reaction?

Reducing the concentration of the reaction
Increasing the pressure of the reaction
Decreasing the pressure of the reaction
Increasing the reaction concentration

Answer 15

Increasing the reaction concentration