New DF

Question 1

What’s the molar volume of gases?

Answer 1

One mole of ANY gas at room temperature and pressure will take up the same volume. This volume is 24dm3 or 24000cm3.

Question 2

What is the ideal gas equation?

Answer 2

pressure (pascals) x volume (m3) = moles x ideal gas constant (8.31) x temperature (kelvin)

Question 3

The shapes of simple molecules and ions

Answer 3

Determined by the number of electron pairs around the central atom and the repulsion between them. Each electron pair naturally repels each other so that the largest bond angle possible exists between the covalent bonds.

Question 4

What does a solid line indicate?

Answer 4

A bond is in the plane of the paper

Question 5

What does a wedged line indicate?

Answer 5

A bond that comes out of the plane of the paper

Question 6

What does a dotted line indicate?

Answer 6

A bond that goes out of the plane of the paper

Question 7

What is a single bond?

Answer 7

A sigma bond

Question 8

What does a double bond consist of?

Answer 8

A pi and sigma bond

Question 9

What is enthalpy change measured under?

Answer 9

Standard conditions of 100kPa pressure and a specified temperature generally 298K.

Question 10

What happens to bonds in an endothermic process?

Answer 10

Bonds are broken

Question 11

What happens to bonds in an endothermic process?

Answer 11

Bonds are broken

Question 12

What happens to bonds in an exothermic process?

Answer 12

Bonds are made

Question 13

How to calculate overall enthalpy change?

Answer 13

(+ve) + (-ve)

Question 14

Enthalpy change of reaction

Answer 14

The enthalpy change when quantities of substances in standard states react completely under standard conditions

Question 15

Enthalpy change of formation

Answer 15

The enthalpy change when 1 mole of a substance is produced from its elements under standard conditions

Question 16

Enthalpy change of combustion

Answer 16

The enthalpy change when 1 mole of a substance is burned completely in oxygen under standard conditions.

Question 17

Enthalpy change of neutralisation

Answer 17

The enthalpy change when solutions of acid and alkali react together under standard conditions to produce 1 mole of water.

Question 18

What is standard conditions?

Answer 18

Solution concentrations of 1.00 moldm-3, pressure 100 kPa and a stated temp (generally 298K).

Question 19

What is calorimetry?

Answer 19

An experimental method for finding enthalpy change by measuring temperature change over time as a reaction occurs. When data is plotted on a graph, data can be extrapolated to give an accurate value for the change in temperature at the beginning of the reaction.

Question 20

what’s the equation for energy change?

Answer 20

Mass (g) x specific heat capacity (J g-1 degrees celsius-1) x temp change ( degrees celsius)

Question 21

What is specific heat capacity?

Answer 21

The energy required to raise 1g of the substance by 1K without a change of state.

Question 22

how can I calculate enthalpy change per mole?

Answer 22

specific heat capacity/ moles

Question 23

What is Hess’s law?

Answer 23

Energy in a reaction must be conserved and it cannot be created or destroyed. The overall enthalpy change for a reaction is the same regardless of the route taken.

Question 24

Enthalpies of formation

Answer 24

Arrows point from the central point C as both A and B are formed from the elements C.

Question 25

Enthalpies of combustion

Answer 25

Arrows point towards the central product (always H2O and CO2) as both A and B burn to form the products at C.

Question 26

What are catalysts?

Answer 26

Lower the activation energy of a reaction by providing an alternative reaction route.

Question 27

What are heterogeneous catalysts?

Answer 27

Catalysts in a different phase or state to the species in a reaction.

Question 28

How does a solid heterogeneous catalyst work?

Answer 28

Works by adsorbing molecules into an active site on the surface of the catalyst. These active sites increase the proximity of molecules and weaken the covalent bonds in the molecules, allowing reactions to occur more easily. This leads to a faster rate of reaction.

Question 29

Where are heterogeneous catalysts used?

Answer 29

In industry to give a surface for the reaction to occur on.

Question 30

What is catalyst poisoning?

Answer 30

Impurities in a reaction mixture may bind to heterogeneous catalysts surface and blocks reactants from being adsorbed. Reduces the activity of the catalyst.