CP 6 - Investigating Reaction Rates Flashcards

1
Q

How can the rate of a reaction be measured (3 ways)?

A

Measure change in mass Measure the volume of gas produced (upside-down measuring cylinder or gas syringe) Observe colour change/ precipitate formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When can the change in mass be used to measure the rate of a reaction? Why?

A

When a gas is produced.

Gaseous molecules will be lost from the reaction vessel so fewer atoms in the reaction mixture. Mass will decrease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do you calculate the rate of reaction?

A

Rate of Reaction =

Amount of product formed or reactant used/Time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Marble chips are added to HCl. How can the rate of reaction be measured?

A

Measure the volume of gas produced (gas syringe or upside-down measuring cylinder) and record the time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why must you be careful when measuring the volume of gas produced using a gas syringe?

A

You must ensure the volume produced will fit within the syringe otherwise it could damage the equipment and cause harm to the user

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why must the bung be immediately attached to the reaction vessel when measuring volume of gas produced?

A

To ensure minimal gas escapes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name 3 ways the rate of reaction between HCl and marble chips could be increased

A

Increased surface area of marble chips Increased concentration of acid Increased temperature of reactants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Dilute HCl is added to sodium thiosulfate. How can the rate of reaction be measured?

A
  • Place piece of paper with a black cross below the reaction vessel and observe this cross through the solution
  • Measure how long it takes for the cross disappear
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why is the precipitate and colour change rate experiment not very reliable?

A

It is very subjective - people might disagree over the exact point when the mark disappears or the solution changes colour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How can you determine the rate of a reaction at a particular time?

A

Plot results on a graph Draw a tangent to the curve at this time Calculate the gradient (change in y ÷ change in x)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Write a chemical equation for the reaction between HCl and marble chips

(CaCO3)

A

2HCl + CaCO 3 ⟶ H 2 O + CaCl 2 + CO 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do you know that a reaction is complete?

A

Mass of reaction mixture/ volume of gas/ colour remain the same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does temperature affect the rate of a reaction? Why?

A

Increasing temperature increases the rate because particles have more kinetic energy so move faster (more frequent collisions) and more particles have energy above the activation energy (more collisions are successful).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does concentration of reactants affect the rate of a reaction? Why?

A

Increasing concentration increases the rate because there are more particles in the same volume so there are more frequent successful collisions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does pressure of reactants affect the rate of a reaction? Why?

A

Increasing pressure increases the rate because there are more particles in the same volume (or the same number of particles in a smaller volume) so there are more frequent successful collisions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly