chem - quiz 2 - 2022

Question 1

For swap and drop: how do you know the charge of the element?

Answer 1

The groups (18) determine the valence electrons - hence determining the charge.

Question 2

What is nitrate?

Answer 2

NO3 ^-1

Question 3

What is sulphate?

Answer 3

SO4^-2

Question 4

What is phosphate?

Answer 4

PO4^-3

Question 5

What is cyanate?

Answer 5

CN^-1

Question 6

What is carbonate?

Answer 6

CO3^-2

Question 7

What is a synthesis reaction?

Answer 7

the building up of compounds by combining elements (when two reactants form new product/s)

Question 8

What is a decomposition reaction?

Answer 8

the break down of compounds into simpler substances - often requires energy in the form of electricity or heat energy

Question 9

What is an acid?

Answer 9

It has a pH level of less than 7 - they taste sour and turn litmus paper red. All acids donate a H+ ion to a base.

Question 10

What is a base?

Answer 10

It has a pH level of greater than 7, all bases has a bitter taste, feel slippery and turn litmus paper blue. A base is any compound that yields hydroxide ions (OH-) when dissolved in water.

Question 11

What is a neutralised reaction?

Answer 11

When an acid and a base are mixed together, the H+ and the OH- combine to make water, the remaining ions form a metal salt. Water is considered neutral (pH of 7)

Question 12

Acid + metal = ?

Answer 12

Acid + metal = salt + hydrogen

Question 13

Acid + base = ?

Answer 13

Acid + base = water + salt

Question 14

Acid + carbonate = ?

Answer 14

Acid + carbonate = salt + water + carbon dioxide

Question 15

Acid + metal oxide = ?

Answer 15

Acid + metal oxide = metal salt + water

Question 16

What is a concentrated acid?

Answer 16

The concentration of an acid is how many molecules of the acid is present in each litre of the solution. A highly concentrated acid has very little water present : e.g., 10M HCl.

Question 17

What is a strong acid?

Answer 17

The strength of an acid is a measure of how readily it is willing to give a hydrogen ion to a base.

Question 18

Observations of a chemical reaction?

Answer 18

• colour change
• odour produced
• temperature change
• precipitate formed
• gas produced/bubbles

Question 19

What does it mean if a compound is soluble?

Answer 19

It can dissolve in a liquid solvent.

Question 20

What is a precipitation reaction?

Answer 20

When two soluble ionic compounds are mixed together to form a precipitate - that is insoluble

Question 21

What is a precipitate?

Answer 21

A precipitate is an insoluble compound that is formed from a reaction of two ionic compounds

Question 22

Where are precipitate reactions used?

Answer 22

Chemists can use them to find out which chemicals are present in a substance or how much of it is present

Question 23

What is a reaction rate?

Answer 23

The “speed” at which a reaction occurs

Question 24

How can the rate of a reaction be increased?

Answer 24

1. increase temp
2. stir the solution
3. increase concentration
4. increase surface area

Question 25

How must the molecules in a compound be in order to react?

Answer 25

For a reaction to occur, the molecules must collide in the correct orientation

Question 26

How does heat increase the rate of reaction?

Answer 26

- particles speed up = more kinetic energy = more likely to collide with the other particles

Question 27

How does surface area increase the rate of reaction?

Answer 27

- increases likelihood of particles reacting with other particles - also called "state of subdivision"

Question 28

How does agitation/stirring increase the rate of reaction?

Answer 28

as the reaction continues, the particles of the reactants get used up, and there are less particles to react with- little collision. to increase this, stirring it, or mixing it can increase the rate of reaction once again

Question 29

How does concentration increase the rate of reaction?

Answer 29

more reactant particles in the same volume if there is a higher concentration - more things to collide with

Question 30

What is a catalyst?

Answer 30

a catalyst is a substance that speed up the reaction but is not used up in the reaction

Question 31

What does a catalyst do?

Answer 31

Some catalysts provide a surface on which the reactants can meet in the correct orientation - where they react to form the products. the products are then released from the catalyst, allowing it to be used again