Physical chemistry

Question 1

what is an exothermic reaction

Answer 1

releasing heat energy to its surroundings (gets hotter)

Question 2

what is an endothermic reaction

Answer 2

absorbing heat energy from its surroundings (gets colder)

Question 3

3.2

Question 4

how to calculate the heat energy change

Answer 4

^Q = mc^T

^Q = energy supplied by water
m = mass of water
c= specific heat capacity of water (4.2)
^T = change in temperature of water

Question 5

how to calculate the molar enthalpy change

Answer 5

Q/J divide by 1000 to get Q/kJ
find moles of fuel using mass/Ar
do Q/kJ divided by moles

Question 6

3.8

Question 7

describe the effects of changes in surface area on the rate of reaction

Answer 7

•increases rate of reaction
•as it it increases the frequency of collisions

Question 8

describe the effects of changes in concentration on the rate of reaction

Answer 8

• increases rate of reaction
• increases frequency of collisions

Question 9

describe the effects of changes in pressure on the rate of reaction

Answer 9

• increases rate of reaction
• increases frequency of collisions

Question 10

describe the effects of changes in temprrature on the rate of reaction

Answer 10

•increases rate of reaction
•higher temperature, more kinetic energy, particles move faster and collide more frequently

Question 11

describe the effects of changes of using a catalyst on the rate of reaction

Answer 11

• increases rate of reaction
• catalysts speed up chemical reactions

Question 12

What is a catalyst

Answer 12

• are substances that speed up chemical reactions without being changed or used up during the reaction

Question 13

How does a catalyst work

Answer 13

• they provide an alternative pathway for a chemical reaction with slower activation energy
• This increases the proportion of particles with energy to react

Question 14

3.15

Question 15

3.16

Question 16

what does this symbol mean —>
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Answer 16

• It is a reversible reaction

Question 17

3.18