Question 1

What is the name of a reaction which transfers energy from the surroundings?

Accepted Answer

Endothermic

Answer

Exothermic

Question 2

What is the name of a reaction which transfers energy to the surroundings?

Accepted Answer

Exothermic

Answer

Endothermic

Question 3

What is an example of an endothermic reaction?

Accepted Answer

Thermal decomposition

Answer

Combustion of fuels

Question 4

What is an example of an exothermic reaction?

Accepted Answer

Combustion of fuels

Answer

Thermal decomposition

Question 5

What is an example of an exothermic reaction?

Accepted Answer

Neutralisation

Answer

Thermal decomposition

Question 6

What happens to the temperature of the surroundings during an endothermic reaction?

Accepted Answer

Decreases

Answer

Increases

Question 7

What happens to the temperature of the surroundings during an exothermic reaction?

Accepted Answer

Increases

Answer

Decreases

Question 8

Which type of reactions are in cold packs?

Accepted Answer

Endothermic reactions

Answer

Exothermic reactions

Question 9

Which type of reactions are in hand warmers?

Accepted Answer

Exothermic reactions

Answer

Endothermic reactions

Question 10

What does the reaction profile of an endothermic reaction look like?

Accepted Answer

The products are at a higher energy level than the reactants

Answer

The reactants are at a higher energy level than the products

Question 11

What does the reaction profile of an exothermic reaction look like?

Accepted Answer

The reactants are at a higher energy level than the products

Answer

The products are at a higher energy level than the reactants

Question 12

The difference between the energy levels of the reactants and products is the

Accepted Answer

energy transferred to/ from the surroundings

Answer

activation energy

Question 13

What is the difference between the reactants energy level and the peak of the curve on the reaction profile?

Accepted Answer

activation energy

Answer

energy transferred to/ from the surroundings

Question 14

What is the activation energy of a reaction?

Accepted Answer

The minimum energy required for a reaction to take place

Answer

The maximum energy required for a reaction to take place

Question 15

Which is an exothermic process?

Accepted Answer

Making bonds

Answer

Breaking bonds

Question 16

Which is an endothermic process?

Accepted Answer

Breaking bonds

Answer

Making bonds

Question 17

BENDOMEX

Accepted Answer

Breaking = Endo Making = Exo

Answer

Breaking = Exo Making = Endo

Question 18

In an exothermic reaction

Accepted Answer

bond breaking energy < bond making energy

Answer

bond breaking energy > bond making energy

Question 19

In an endothermic reaction

Accepted Answer

bond breaking energy > bond making energy

Answer

bond breaking energy < bond making energy

Question 20

Which is the definition for standard enthalpy of neutralisation?

Accepted Answer

enthalpy change when one mole of water is formed in a reaction between an acid and alkali under standard conditions

Answer

enthalpy change when one mole of a substance is formed from its constituent elements with all reactants and products in standard states under standard conditions

Answer

enthalpy change when one mole of a substance is completely burned in oxygen with all reactants and products in standard states under standard conditions

Question 21

Which is the definition for standard enthalpy of combustion?

Accepted Answer

enthalpy change when one mole of a substance is completely burned in oxygen with all reactants and products in standard states under standard conditions

Answer

enthalpy change when one mole of water is formed in a reaction between an acid and alkali under standard conditions

Answer

enthalpy change when one mole of a substance is formed from its constituent elements with all reactants and products in standard states under standard conditions

Question 22

Which is the definition for standard enthalpy of formation?

Accepted Answer

enthalpy change when one mole of a substance is formed from its constituent elements with all reactants and products in standard states under standard conditions

Answer

enthalpy change when one mole of water is formed in a reaction between an acid and alkali under standard conditions

Answer

enthalpy change when one mole of a substance is completely burned in oxygen with all reactants and products in standard states under standard conditions

Question 23

What is an enthalpy change?

Accepted Answer

Heat change at a constant pressure under standard conditions

Answer

Temperature change at a constant pressure under standard conditions

Question 24

What is heat?

Accepted Answer

The total amount of energy of all the particles in a given amount of substance

Answer

The average kinetic energy of particles in a system

Question 25

What is temperature?

Accepted Answer

The average kinetic energy of particles in a system

Answer

The total amount of energy of all the particles in a given amount of substance

Question 26

Products of neutralisation

Accepted Answer

salt and water

Answer

salt (metal + acid ending) and water

Answer

carbon dioxide and water

Question 27

Products of combustion

Accepted Answer

carbon dioxide and water

Answer

salt and water

Question 28

Why might the value of ∆cH obtained by calorimetry be different from the value calculated from thermochemical cycles/enthalpy diagrams?

Accepted Answer

Heat loss/ some heat absorbed by the apparatus , incomplete combustion may have also taken place, some water/fuel may have vapourised, reactants/ products may not be in their standard states

Answer

not measuring the heat accurately enough

Question 29

When carrying out a calorimetry practical how can you compensate for the heat loss to surroundings (esp when a reaction is quick)

Accepted Answer

By extrapolating the cooling part of the graph back to the time of mixing to give a better estimate of what the maximum temperature would be in the absence of any heat loss. You plot enough points before mixing in order to be sure that the liquid is at constant room temperature. Then you get a quick rise in temperature as the reaction happens before it starts to cool again. Once you have established that the cooling is happening at a steady rate, you extrapolate the cooling curve back to the point of mixing to give a reasonable estimate of the temperature rise you would have got if there was no cooling.

Answer

By extrapolating the heating part of the graph back to the time of mixing to give a better estimate of what the maximum temperature would be in the absence of any heat loss. You plot enough points before mixing in order to be sure that the liquid is at constant room temperature. Then you get a quick rise in temperature as the reaction happens before it starts to cool again. Once you have established that the cooling is happening at a steady rate, you extrapolate the cooling curve back to the point of mixing to give a reasonable estimate of the temperature rise you would have got if there was no cooling.

Question 30

q =

Accepted Answer

m x c x change in T

Answer

m x c x change in K

Question 31

Standard enthalpy change =

Accepted Answer

q (in kJ) / number of moles

Answer

q (in J) x number of moles

Question 32

n (moles ) =

Accepted Answer

concentration x v (in dm3)

Answer

concentration x v (in cm3)

Question 33

n (moles)

Accepted Answer

mass / Mr

Answer

Mr / mass

Question 34

How can you calculate Mr?

Accepted Answer

add all the atomic masses

Answer

add all the atomic numbers

Question 35

Which elements are diatomic? (found in molecules of 2)

Accepted Answer

oxygen, nitrogen, hydrogen, chlorine, fluorine, bromine and iodine

Answer

carbon, sillicon, sulphure, chlorine, bromine, fluorine and iodine

Question 36

state of iodine at rtp

Accepted Answer

solid

Answer

liquid

Answer

gas

Question 37

state of chlorine at rtp

Accepted Answer

gas

Answer

liquid

Answer

solid

Question 38

state of bromine at rtp

Accepted Answer

liquid

Answer

gas

Answer

solid

Question 39

state of fluorine at rtp

Accepted Answer

gas

Answer

liquid

Answer

solid

Question 40

dm3 to cm3

Accepted Answer

x 1000

Answer

/ 1000

Question 41

kJ to J

Accepted Answer

x 1000

Answer

/ 1000

Question 42

J to kJ

Accepted Answer

/ 1000

Answer

x 1000

Question 43

cm3 to dm3

Accepted Answer

/ 1000

Answer

x 1000

Question 44

What are standard conditions

Accepted Answer

298K and 100kPa/1atm

Answer

298K and 1000kPa/10 atm

Question 45

What does Hess's Law state?

Accepted Answer

Enthalpy change in a reaction is independent of the route it takes (as long as the starting and ending positions are the same)

Answer

Energy change in a reaction is independent of the route it takes (as long as the starting and ending positions are the same)

Question 46

In order to write in the values for standard enthalpy of formation you must:

Accepted Answer

make sure the arrow starts with the elements and ends with the substance (for which the value is provided)

Answer

make sure the arrow starts with the substance (for which the value is provided) and ends with the products of combustion (nearly always CO2 + H2O)

Question 47

In order to write in the values for standard enthalpy of combustion you must:

Accepted Answer

make sure the arrow starts with the substance (for which the value is provided) and ends with the products of combustion (nearly always CO2 + H2O)

Answer

make sure the arrow starts with the elements and ends with the substance (for which the value is provided)

Question 48

To work out total energy change

Accepted Answer

Energy taken in to break bonds - energy released when bonds are formed

Answer

Energy released when bonds are formed - energy taken in to break bonds

Question 49

nitrate ion

Accepted Answer

NO3 (-1 charge)

Answer

NO3 (-2 charge)

Question 50

sulphate ion

Accepted Answer

SO4 (2- charge)

Answer

SO4 (1- charge)

Question 51

carbonate ion

Accepted Answer

CO3 (2- charge)

Answer

CO3 (1- charge)

Question 52

Sulphuric acid forms salts ending with

Accepted Answer

sulphate

Answer

chloride

Answer

nitrate

Question 53

Hydrochloric acid forms salts ending with

Accepted Answer

chloride

Answer

sulphate

Answer

nitrate

Question 54

Nitric acid forms salts ending with

Accepted Answer

nitrate

Answer

chloride

Answer

sulphate

Question 55

When drawing hess cycles you must

Accepted Answer

make sure arrows are according to the definitions of values quoted, equations are balanced

Answer

make sure arrows are opposite to the definitions of values quoted, equations are balanced

Question 56

In order to calculate enthalpy change from heat evolved you must

Accepted Answer

convert J to kJ (divide by 1000)

Answer

convert kJ to J (multiply by 1000)

Question 57

How many bonds does O make?

Accepted Answer

2

Answer

4

Answer

1

Question 58

How many bonds does C make?

Accepted Answer

4

Answer

2

Answer

1

Question 59

How many bonds does H make?

Accepted Answer

1

Answer

2

Answer

4

Question 60

when do you add a - sign in front of your answer?

Accepted Answer

calorimetry questions IF temperature ROSE

Answer

hess cycle questions IF temperature ROSE

Question 61

For calorimetry neutralisation questions which moles would you divide q by?

Accepted Answer

the lower moles, not in excess (also 1:1 mole ratio with the water)

Answer

the higher moles, in excess (also 1:1 mole ratio with the water)

Question 62

To work out the standard enthalpy change of a reaction

Accepted Answer

reactants - products

Answer

products - reactants

Question 63

Why is the standard formation of an element 0?

Accepted Answer

they are elements already in their standard states and so are 0 by definition

Answer

nothing needs to happen

Question 64

What is a bond dissociation enthalpy

Accepted Answer

The enthalpy change required to break a covalent bond

Answer

The average value of the bond dissociation enthalpy for a given type of bond taken from a range of different compounds

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