Chemistry || Rates Of Reaction C18

Question 1

Independent Variable?

Answer 1

Variable in practical that you change,

This is always the x axis on the graph.

Question 2

Dependant Variable?

Answer 2

Variable that you can measure and usually don’t change,

This is always the y axis on the graph.

Question 3

Core Practical?

Answer 3

Measuring rate when affected by temperature, surface area and concentration,

Putting marble chips in a beaker with dilute hydronic acid,
Time this but each time, make the marble chips smaller and smaller,
The smaller the chips, the quicker the reaction because the surface area is smaller,

Repeat this experiment but increase concentration of HCL instead and keep the marble chips the same,
The higher the concentration, the quicker the reaction,

Sodium thiosulfate and hydraulic acid react together to form a yellow precipitate of sulphur,
Measure the time it takes for the yellow precipice to form and cloud the water,
You shouldn’t be able to see a cross through the bottom of the glass,
Measure this with different temperatures.

Question 4

Exothermic?

Answer 4

Reactants start with more energy and products end with less,

Energy is GIVEN OUT,

A reaction is exothermic when the reaction is a negative number.

Question 5

(Triangle)H Means What? 🔺H

Answer 5

Do:

Energy Realised

Question 6

Endothermic?

Answer 6

The reactants energy is more than the products energy,

Energy is TAKEN IN,

If the number is positive, the reaction is an endothermic reaction.

Question 7

Redox Reaction?

Answer 7

When oxidation and reduction happens at the same time,

In halogens, halide ions loose electrons (oxidation) and the halogens gain electrons (reduction).

Question 8

Group 7?

Answer 8

Halogens,

7 electrons in the outer shell,

Diatomic molecules (they share one pair of electrons in a covalent bond so they only exist as Br2, Cl2, I2),

Go down group, the melting point gets higher because it’s harder for the electron to be gained,

This is because the outer shell is further from the nucleus so it’s harder to connect,

Form 1- ions.

Question 9

Chlorine?

Answer 9

A green gas.

Question 10

Bromine?

Answer 10

Red/Brown liquid that turns orange in room temperature.

Question 11

Iodine?

Answer 11

Grey solidly that turns purple in heat.

Question 12

Group 1?

Answer 12

Alkali Metals,

All have one outer electron,

Low melting point,

Soft to cut,

They form ionic compounds,

Very reactive,

Get more reactive as you go down the group because it’s easier to loose one electron,

This is because the electron is further from positive nucleus,

Forms hydrogen and a metal hydroxide when it reacts with water,

Equation With Water:
2K + H2O ——> H2 + 2KOH

Question 13

Test For Chlorine?

Answer 13

Use a damp piece of blue litmus paper,

It will turn white in chlorine.

Question 14

Group 0?

Answer 14

Noble Gasses,

All inert!,

Have a full outer shell already,

All colourless at room temperature,

Not flammable,

Boiling point, melting point and density increase as you go down the group.

Question 15

Group 1 And Water Reaction?

Answer 15

Forms hydrogen and a metal hydroxide when it reacts with water,

Eg. Potassium + Water —> Potassium Hydroxide and Hydrogen.

Question 15

Group 2 And Water Reaction?

Answer 15

Forms hydrogen and a metal hydroxide when it reacts with water,

Eg. Calcium + Water —> Calcium Hydroxide and Hydrogen.

Question 16

Group 7 And Hydrogen Reaction?

Answer 16

Form hydrogen halides,

Hydrogen halides are soluble, they dissolve in water to form acidic solutions,

E.g. Hydrogen + Chlorine —> Hydrogen Chloride.

Question 17

Group 7 And Metal Reaction?

Answer 17

Form metal halides,

Metal halides are just salts but we give them a fancy name,

E.g. Sodium + Chlorine —> Sodium Chloride.

Question 18

Displacement Reaction?

Answer 18

A more reactive halogen will displace a less reactive one,

Reactivity increases as you go up group 7 so fluorine will displace Chlorine for example.

Question 19

Predicting Physical Properties Of Group 7?

Answer 19

Melting point increases down group 7 so solids are at the bottom of the table and gases are at the top,

The colour of the halogen gets darker as you go down group 7,

E.g. Asatine is a dark coloured, black, solid and is at the bottom of group 7.