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Biblioteka

Year 10 Energy changes

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Pitanje 1
1.

Identify the type of change for the reaction: NaCl(s) + H₂O(l) → NaCl(aq)

a salts dissolving in water b neutralisation reactions c displacement reactions d precipitation reactions

Pitanje 2
2.

Identify the type of change for the reaction: NaOH + HCl → NaCl + H₂O

a salts dissolving in water b neutralisation reactions c displacement reactions d precipitation reactions

Pitanje 3
3.

Identify the type of change for the following reaction: Cl₂ + 2NaBr → 2NaCl + Br₂

a salts dissolving in water

b neutralisation reactions

c displacement reactions

d precipitation reactions

Pitanje 4
4.

Identify the type of change for the following reaction: Fe + CuSO₄ → FeSO₄ + Cu

a salts dissolving in water b neutralisation reactions c displacement reactions d precipitation reactions

Pitanje 5
5.

Identify the type of change for the reaction: AgNO₃(aq) + NaCl(aq) → NaNO₃(aq) + AgCl(s)

Hint - look at the state symbols

Pitanje 6
6.

In an exothermic reaction, heat energy is:_________________ to the surroundings.

Pitanje 7
7.

In an endothermic reaction, heat energy is:________________________ from the surroundings.

Pitanje 8
8.

Bond breaking is:

Pitanje 9
9.

Bond forming is:

Pitanje 10
10.

In an exothermic reaction:

Pitanje 11
11.

In an endothermic reaction:

Pitanje 12
12.

What is the minimum energy needed to break the bonds in the reactants is called energy.

Drugi mogući odgovor:
activation
Pitanje 13
13.

Combustion of methane

This is a reaction profile diagram for an reaction. (1 Point)

Energy needed to break the bonds in the (the energy)

is less than the energy released when the bonds form in the .

Copy this diagram and explanation into your exercise books.

Drugi mogući odgovor:
exothermic
products
reactants
endothermic
activation
Pitanje 14
14.

Respiration

This is a reaction profile diagram for an reaction. (1 Point)

Energy needed to break the bonds in the (the energy)

is less than the energy released when the bonds form in the .

Drugi mogući odgovor:
activation
products
exothermic
reactants
endothermic
Pitanje 15
15.

Which letter represents the activation energy? A, B, or C? (1 Point)

Pitanje 16
16.

Which letter represents the overall energy change? (1 Point)

Pitanje 17
17.

Which letter represents the energy change for breaking bonds? A, B, or C? (1 Point)

Pitanje 18
18.

Which letter represents the energy change for making bonds?

Note the arrow should be going downwards but this was a multiple choice question.

Pitanje 19
19.

The energy change is endothermic or exothermic. (1 Point)

Pitanje 20
20.

In this change, would the surroundings get hotter or cooler?

exothermic

Pitanje 21
21.

In this change, the temperature of the surroundings would (1 Point) increase or decrease?

Pitanje 22
22.

Calculate the energy change.

Total energy taken in to break bonds in the reactants

= 4 x C-H + 2 x O=O

= 4 x 414 + 2 x 498 = 2652 kJ / mol

Total energy given out when bonds form in products

= 2x C=O + 4 x O-H

= 2 x 803 + 4 x 464

= kJ/mol

Energy change = energy to break bonds - energy to make bonds

= 2652 - 3462 = sign value kJ/mol.

Note this is an reaction so energy is released to the surroundings and the temperature of the surroundings

Pitanje 23
23.

This reaction profile shows an reaction.

Activation energy =

Energy needed to break bonds in reactants =

Energy released when new bonds form in the products =

Energy change in the reaction =

Energy in to break bonds is less than energy released to make bonds so the reaction is .

The reaction takes in energy so the surrounding will lose energy and the temperature will

Drugi mogući odgovor:
decrease
B
increase
exothermic
A
endothermic
B
Pitanje 24
24.

Which letter represents the activation energy?

Pitanje 25
25.

Which letter represents the energy needed to break the bonds in the reactants? A, B, or C? (1 Point)

Pitanje 26
26.

Which letter represents the energy needed to form the bonds in the products? (1 Point)

Pitanje 27
27.

Which letter represents the energy change for the reaction? (1 Point)

Pitanje 28
28.

The temperature of the surroundings will:

Pitanje 29
29.

Please choose the correct statement.

Pitanje 30
30.

Energy needed to break the bonds in the reactants

= 1 x N=N + 1 x O=O

= 945 + 498

= kJ/mol

Energy given out when bonds form in the products

= 2 x N=O

= 2x 630

= kJ/mol

Energy change = energy needed to break bonds - energy released when bonds form

= 1413 - 1260

= sign value

The energy change is positive so the reaction is and the temperature of the surroundings will

Pitanje 31
31.

Stavka koja se može prevućiarrow_right_altOdgovarajuća stavka

Sum of energy to make bonds

arrow_right_alt

4 x C-H + Cl-Cl

Bond broken =

arrow_right_alt

= 4 x 413 + 243

Energy change formula

arrow_right_alt

= 1895 kJ / mol

Energy to make bonds

arrow_right_alt

3 x C-H + 1 x C-Cl + H-Cl

Energy change calculation

arrow_right_alt

= 3 x 413 + 327 + 432

Reaction is

arrow_right_alt

= 1998

Bonds made =

arrow_right_alt

= bonds broken - bonds made

Energy change value

arrow_right_alt

1895 - 1998

Energy to break bonds

arrow_right_alt

-103 kJ/mol

Sum of energy to break bonds

arrow_right_alt

exothermic