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GCSE Chem > Topic 7 > Flashcards

Topic 7 Flashcards

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1
Q

7.1
Devise an experiment to investigate the effect of concentration
on the rate of reaction

A

-10cm³ sodium thiosulfate (w/ measuring cylinder) into conical flask
-10cm³ HCl to same cf
-Cf on black cross
-Record t taken (w/ stop clock) for ╳ to disappear
-Repeat w/ diff concs sodium thiosulfate
-Repeat whole experi & work out mean for each conc

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2
Q

7.1
Devise an experiment to investigate the effect of temperature on the rate of reaction [3 marks]

A

-Water bath to heat solution to desired temp
-Record (w/ stop clock) t for colour change to occur -> obscure cross
-Repeat w/ diff temps
-Ensure same v of solution used each t

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3
Q

7.1
Devise an experiment to investigate the effect of using small vs large marble chips on the rate of reaction

A

-Fixed v (measuring cylinder) HCl in conical flask
-Fixed m (balance) SMALL marble chips in flask
-Stopper flask w/ bung + delivery tube
-Delivery tube into trough filled w/ water
-Upturned measuring cylinder over tube
-H₂ gas trapped in cylinder
-Measure gas v every 30 secs
-Continue until no more H₂ produced
-Repeat w/ same mass LARGE marble chips

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4
Q

7.1 7.3
State 4 ways the rate of reaction can be increased

A

-↑ temp
-↑ pressure
-↑ conc
-Catalyst

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5
Q

7.2
Suggest 4 methods of determining the rate of reaction

A

-Collection of gas w/ gas syringe
-Collection of gas over water
-Monitor change in mass of gas (gas mass change)
-Monitor colour change

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6
Q

7.2
What does the reaction between calcium carbonate and hydrochloric acid produce?

A

Calcium chloride + Water + Carbon dioxide

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7
Q

7.2
What does the reaction between magnesium and hydrochloric acid produce?

A

Magnesium chloride + Hydrogen gas

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8
Q

7.2
The change in the mass of a gas is monitored by placing marble chips into a solution of hydrochloric acid. The top is sealed with cotton wool. Explain what would happen to the reading on the balance

A

-↓
-CO₂ can escape

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9
Q

7.3
Why do most reactions slow down overtime

A

Reactants are used up

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10
Q

7.3
What is a successful collision?

A

Produces reaction

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11
Q

7.3
Suggest a way you could monitor the rate of reaction over time during a practical

A

Use gas syringe
(measures change in v)

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12
Q

7.4
Explain the effect of increasing temperature on the rate of reaction

A

-Gain KE -> faster
-↑ frequent, successful collisions
-r. reaction ↑

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13
Q

7.4
Explain the effect of increasing concentration on the rate of reaction

A

-↑ particles closer together in same given v
-↑ frequent successful collisions
-r. reaction ↑

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14
Q

7.4
Explain the effect of increasing pressure on the rate of reaction

A

-Less space -> closer together
-↑ frequent successful collisions
-r. reaction ↑

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15
Q

7.4
Explain the effect of increasing surface area on the rate of reaction

A

-↑ particles exposed to reactant
-↑ frequent successful collisions
-↑ r. reaction

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16
Q

7.5
State the equation used to calculate the rate of reaction

A

r. reaction = change in amount of reac or prod/time

(usually the gradient)

17
Q

7.6
Define the term catalyst

A

-Speeds up r. reaction
-W/o altering products
-Its m remains unchanged

18
Q

7.6
Why are catalysts useful in industry?

A

-↓activation E
-Allow reactions to occur at ↓ temp + pressure
-↓ E cost required to ↑ temp + pressure

19
Q

7.6
Platinum is a very expensive catalyst. Suggest why this does not matter

A

Not used up -> can be re-used

20
Q

7.7
Describe how catalysts increase the rate of reaction

A

-Provide alternate pathway
-W/ lower activation E

(Note: doesn’t increase frequency of collisions. Increases frequency of successful collisions bc particles have greater activation E)

21
Q

7.7
Explain why catalysts in catalytic converters in car exhausts are spread onto a honeycomb structure rather than used as large pieces

A

-↑ SA
-↑ successful frequent collisions
-↑ r. reaction

22
Q

7.7
Explain why catalysts are more effective when the engine has been running for a short time rather than when the engine is first started

A

-Catalyst heats up
-Reaction faster as particles have more KE so move faster

23
Q

7.8
What is an enzyme? What is one use they have?

A

-Biological catalyst
-Speeds up r. reaction

-Produce alcoholic drinks

24
Q

7.8
Compare biological and chemical catalysts

A

-Both lower activation E -> speed r. reaction

-Bio: Specific to certain reactions, denatured by heat/pH
-Chemical: More resistant to heat/pH

25
Q

7.9
a) Name 4 chemical reactions that experience a change in heat energy (energy transferred to or from the surroundings)
b) How can the heat change be measured?

A

a) -Salt dissolve in water
-Neutralisation
-Displacement
-Precipitation
b) Thermometer

26
Q

7.10
What is an exothermic reaction?

A

Heat E given out

27
Q

7.11
What is an endothermic reaction?

A

Heat E taken in

28
Q

7.12
What type of reaction (endo or exo) is
a) making bonds
b) breaking bonds

A

a) exo
b) endo

29
Q

7.13
When will the overall heat energy change for a reaction be exothermic? When will it be endothermic?

A

Exo
-↑ heat E released when forming bonds than breaking
Endo
-↑ heat E released when breaking bonds than forming

30
Q

7.14
Calculate the energy change when hydrogen and chlorine react to form hydrogen chloride
H-H + Cl-Cl -> 2H-Cl
State whether the reaction is exothermic or endothermic

Bond energies:
H-H = 436 kJ mol-¹
Cl-Cl = 243 kJ mol-¹
H-Cl = 432 kJ mol-¹

A

H-H
1 × 436 = 436
Cl-Cl
1× 243 = 243
Total E in (bonds broken) = 679

2H-Cl
2 × 432 = 864
Total E out (bonds made) = 864

E change = E in - E out
= 679 - 864
= -185 kJ mol -¹

Exothermic (bc negative sign)

31
Q

7.15
Define the term activation energy

A

Min amount of E required for reaction to occur

32
Q

State the formula for calcium carbonate

A

CaCO₃

GCSE Chem (13 decks)

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