Chapter 18, Problem 109A

(a)

Interpretation Introduction

Interpretation: The grams of sucrose that decompose in the first 30 minutes are to be calculated.

Concept Introduction: The rate is a method for determining how much something changes over a predetermined period of time. The amount of reactant or product that changes per unit of time is the reaction rate.

Answer to Problem 109A

The grams of sucrose that decompose in the first 30 minutes are $\text{3}\text{g}$ .

Explanation of Solution

Mass of sucrose before decomposition is $\text{10}\text{g}$ .

In 30 minutes, the mass of sucrose goes from $\text{10}\text{g}$ to $7\text{g}$ .

The mass of sucrose that is decomposed in first 30 minutes is given as

  $10\text{g}-7\text{g}\text{=}\text{3}\text{g}$

(b)

Interpretation Introduction

Interpretation: The grams of sucrose decompose in the interval between 90 minutes and 120 minutes are to be calculated.

Concept Introduction: The rate is a method for determining how much something changes over a predetermined period of time. The amount of reactant or product that changes per unit of time is the reaction rate.

Answer to Problem 109A

The grams of sucrose decompose in the interval between 90 minutes and 120 minutes are $\text{1}\text{.3}\text{g}$ .

Explanation of Solution

According to the graph, the mass of sucrose in 90 minutes is $2.5\text{g}$ .

The mass of sucrose in 120 minutes is $1.2\text{g}$ .

The mass of sucrose that is decomposed between 90 minutes and 120 minutes is given as

  $2.5\text{g}-1.2\text{g}\text{=}\text{1}\text{.3}\text{g}$

(c)

Interpretation Introduction

Interpretation: The rate of decomposition with time is to be explained.

Concept Introduction: The rate is a method for determining how much something changes over a predetermined period of time. The amount of reactant or product that changes per unit of time is the reaction rate.

Answer to Problem 109A

The rate of decomposition with time is decreased.

Explanation of Solution

From the graph, the range of rate and time can be interpreted.

As the mass of sucrose is decomposed over time, it means that there is a gradual decrease in rate.

As time increases, the rate decreases.

The rate gets decreased as the decomposition occurs over time.