6 - Chemical Reactions Flashcards

Question

What colour is the Manganate ion? (MnO₄^-)

Answer 1

Colourless

Answer 2

- Wax melting - Wax solidifying - Wax evaporating - Wax softening - Air particles vibrate faster

Answer 3

- Combustion of wax - Smoke formed - Combustion of wick

Answer 4

A change in which no new substances are formed, particles remain the same | e.g dissolving or state changes

Answer 5

A change in which a new substance is formed | e.g Chemical reaction like combustion

Answer 6

The gradient of a line

Answer 7

Rate of Reaction = Δy/Δx

Answer 8

Rate = Δmass/Δtime | measured in g/s

Answer 9

Hydrogen and sodium hydroxide

Answer 10

The rate of reaction at first is fast (steep gradient) to start with, but then slows down (shallow gradient)

Answer 11

The variable that is changed during an experiment

Answer 12

The variable that is measured during an experiment

Answer 13

The variables that are kept the same during a chemical reaction

Answer 14

1. Particles must collide in order for a reaction to occur 2. Particles require minimum energy, the activation energy, in order to break their bonds and react 3. If particles have sufficient energy, then the collision will be successful 4. Not all collisions are successful 5. In order to increase the rate of reaction, we must increase the chance of a successful collision

Answer 15

- Smaller chips have a bigger surface area so more particles are exposed - This means that collisions are more frequent/there are more collisions per second - Therefore there is a higher frequency of successful collisions

Answer 16

- The pressure causes particles to be forced closer together - This means that collisions are more frequent/there are more collisions per second - Therefore there is a higher frequency of successful collisions

Answer 17

- The higher concentration means that there are more acid particles per unit volume - this means collisions are more frequent - Therefore there is a higher frequency of successful collisions

Answer 18

- The particles in high temperature have higher energy that cold ones - This means that a greater proportion of the collisions have the activation energy needed for a successful collison, and due to the increase in energy of the particles, they will also move faster and there will be more collisions per second - Therefore there is a higher frequency of successful collisions

Answer 19

- The catalyst reduces the activation energy needed for a successful collision - More particles possess the energy needed for a successful collision - Therefore there is a higher frequency of successful collisions

Answer 20

- The temperature is lowered, resulting in a decrease of energy for each particle, so a smaller proportion of the particles have the activation energy required for a successful collision. - Frozen particles will vibrate on the spot instead of moving around due to their lack of energy, drastically reducing the number of collisions - Therefore here is a lower frequency of succesful collisions

Answer 21

Reactions where the products can return and become the reactents once again

Answer 22

- Physical changes are usually reversible - Only some chemical changes are reversible

Answer 23

- Temperature - Surface area - Type of metal used - Concentration of acid (in Moles) - Amount of reactants used - Pressure

Answer 24

The reaction occuring the other way down will be the opposite e.g. if one way, it is endothermic requires 30J of energy, the other way it will be exothermic and release 30J

Answer 25

Hydrated salts are bonded with water molecules while anhydrous salts have no water

Answer 26

1. The reversible reaction must be in a closed system 2. The forward and backward reactions occur at the same rate 3. The concentration of the reactants & products stays the same

Answer 27

Equilibrium is on the **left**

Answer 28

Equilibrim is in the **middle**

Answer 29

Equilibrium is on the right

Answer 30

The proportion of reactants & products at equilibrium

Answer 31

Whenever a system is subjected to a change, a reaction will occur to oppose the change and return to equilibrium

Answer 32

- Temperature - Proportion of reactants to products - Pressure, if the reaction is gaseous - Catalysts

Answer 33

If temperature is increased, the endothermic reaction will occur to reduce the temperature and the equilibrium will shift in the direction of this reaction. Likewise, if the temperature decreases, an exothermic reaction will occur.

Answer 34

If more reactants are added, the forward reaction will occur to reduce the concentration of the reactants and restore the pressure. The position of equilibrium therefore moves to the right. | And, of course, vice versa

Answer 35

For gaseous reactions ONLY - If the pressure is increased, a reaction will occur to decrease the number of moles of gas and therefore reduce the pressure. The position of equilibrium moves to the side with less moles of gas. | And, of course, vice versa

Answer 36

A catalyst speeds up both the forward and backward reactions equally and therefore does not affect the position of equilibrium. However, it is useful to speed up reactions such as the haber process where the products are constantly being removed. | Important - The position does not change

Answer 37

N₂ + 3H₂ ⇌ 2NH₃

Answer 38

1. The reaction CH₄ + 2H₂O → CO₂ + 2H₂ is used to produce hydrogen, and Nitrogen is extracted from the air 2. These get forced to a pressure of 200 atm to get optimum percentage yield of ammonia 3. Iron catalyst beds are used to speed up the reaction which produces ammonia, so it is produced faster 4. The ammonia is removed during the process by beng cooled to -10 degrees by a cooling tank 5. The Nitrogen and Hydrogen which did not react, the majority, is recycled back to make the reaction occur again and not be watsted | To give an idea, this process has a 15% yield

Answer 39

CH₄ + 2H₂O → CO₂ + 2H₂

Answer 40

The very high pressure, 200 atm, causes the position of equilibrium to move to the side of the reaction with less moles. This is ammonia, which has only 2 moles compred to the 4 moles of Hydrogen nánd Nitrogen on the other side. Therefore there is a higher yield of ammonia.

Answer 41

A temperature that would be too high would favour the endothermic backward reaction, but any temperature below 450 degrees would result in the haber process occuring too slowly (which is not economically favourable) because the particles do not have enough activation energy.

Answer 42

The catalyst speeds up bothe the forward and backward reactions so the equilibrium does not change, but ammonia is produced and can be therefore removed more quickly

Answer 43

2SO_{2 (g)} + O_{2 (g)} ⇌ 2SO_{3 (g)}

Answer 44

- Combustion of sulfur - Roasting sulfite ore with oxygen

Answer 45

- 450 degrees Celsius - 2atm/200kPa - Vanadium (V) Oxide Catalyst

Answer 46

- **Efficiency** - The catalyst speeds up the reaction so more of the product can be removed - **Economy** - Using a catalyst is less expensive than increasing other conditions such as pressure - **Safety** - A catalyst is safer to use that an increased pressure