Chapter U5.13, Problem 4E

(a)

Interpretation Introduction

Interpretation: The factor that determines the speed of reaction of lighting charcoal for a barbecue needs to be explained.

Concept Introduction : Rate of a reaction is the speed at which a reaction occurred. There are many factors that affect the rate of a chemical reaction, such as, temperature, concentration, surface area etc.

Answer to Problem 4E

Increasing surface area of charcoal, speeds up the reaction of lighting charcoal.

Explanation of Solution

For a reaction to occur, the collision of reactant particles in correct orientation with sufficient energy is required. Surface area is one of the factors that affect the rate of chemical reaction. If the surface area of a reactant is increased, it is more exposed to other reactant and hence increases speed of reaction. So, grinding charcoal to small pieces increases rate of reaction.

(b)

Interpretation Introduction

Interpretation: The factor that determines the speed of reaction of baking cupcakes needs to be explained.

Concept Introduction : Rate of a reaction is the speed at which a reaction occurred. There are many factors that affect the rate of a chemical reaction, such as, temperature, concentration, surface area etc.

Answer to Problem 4E

Increasing temperature of the oven results increases baking of cupcakes.

Explanation of Solution

Temperature is one of the factors that affect the rate of reaction. Increase of temperature results increase of the average kinetic energy of reactant molecules. This results the rapid movement of particles and hence more collision occurs. So, for baking of cupcakes increase of temperature of the oven increase the rate of the reaction.

(c)

Interpretation Introduction

Interpretation: The factor that determines the speed of reaction of dissolving sugar in water needs to be explained.

Concept Introduction : Rate of a reaction is the speed at which a reaction occurred. There are many factors that affect the rate of a chemical reaction, such as, temperature, concentration, surface area etc.

Answer to Problem 4E

Increase of temperature speed up the reaction of dissolving sugar in water.

Explanation of Solution

Temperature is one of the factors that affect the rate of reaction. Increase of temperature results increase of the average kinetic energy of reactant molecules. This results the rapid movement of particles and hence more collision occurs. Solubility of substance depends on temperature. Increasing temperature results more solubility of sugar in water.

(d)

Interpretation Introduction

Interpretation: The factor that determines the speed of reaction of removing a stain from clothing is to be explained.

Concept Introduction: Rate of a reaction is the speed at which a reaction occurred. There are many factors that affect the rate of a chemical reaction, such as, temperature, concentration, surface area etc.

Answer to Problem 4E

Speed of reaction of removing a stain from clothing can be increased by using catalysts.

Explanation of Solution

Stains are composed of different molecules. So, some enzymes are used to remove stains. Enzymes are the catalysts that speed up the reaction. Proteases can break down proteins, so it is good for removing protein stains such as, blood, gravy etc. Lipase can break down grease and fats. These enzymes are present in washing powders. So, using catalysts increase the reaction of stain removal.