Speed of Reaction

True of false?

Speed of reaction refers to how fast the reactants are used up in a reaction or how fast the products are formed in a reaction.

• TRUE

• FALSE

We can measure the speed of reaction by measuring the

• mass of reactants remaining in a period of time

• size of the solid reactant remaining

• time taken for a reaction to be completed

• volume of gas produced in a period of time

Which factors affect the speed of a reaction?

• concentration

• particle size

• temperature

• all of these

An increase in temperature causes the reacting particles to ......

• lose energy and move slower; hence decreasing frequency of effective collisions.

• gain energy and move faster; hence increasing the frequency of effective collisions.

• lose energy and move faster; hence increasing the frequency of effective collisions.

• gain energy and move slower, hence decreasing the frequency of effective collisions.

Why does a lower concentration of reactant decrease the rate of reaction?

• it decreases the number of particles per unit volume, hence decreases the frequency of effective collisions

• it lowers the activation energy, hence decreases the frequency of effective collisions

• it lowers the energy of the colliding particles, hence decreases the frequency of effective collisions

When mixed with dilute acid, magnesium powder reacts faster than magnesium strip because

• smaller particles have smaller surface area.

• smaller particles have larger surface area.

• small and large particles have the same surface area.

• 

When pressure is increased, what happens to the particles of a gas?

• The particles spread further apart and decreases the frequency of effective collisions.

• The paricles spread further apart and increases the frequency of effective collisions.

• The particles are forced closer together and increases the frequency of effective collisions.

• The particles are forced closer together and decreases the frequency of effective collisions.

Which chemical reactions will be affected by a change in pressure? 

The speed of reaction graph shown was obtained when zinc was added to hydrochloric acid. What does the vertical axis represent?

• mass of gas            

• mass of reactants

• volume of acid

• volume of gas

The graph shows how the total volume of a gas given off from a reaction changes with time. In which time interval is least volume of gas given off?

• A

• B

• C

• D