C5 - chemical changes

Question 1

how is the position of the metals in the reactivity series decided?

Answer 1

By how easily they lose electrons

Question 2

Metal + acid -> …

Answer 2

salt + hydrogen

Question 3

Metal + water -> …

Answer 3

metal hydroxide + oxygen

Question 4

metal + oxygen -> …

Answer 4

metal oxide

Question 5

elements bellow carbon in the reactivity series are Extracted using what method?

Answer 5

Electrolysis

Question 6

Elements below cobbling the reactivity series are extracted using what method

Answer 6

Displacement using carbon or thermal decomposition

Question 7

What does it mean if an ore is high-grade

Answer 7

it contains a high percentage of the metal

Question 8

what equipment is used during electrolysis?

Answer 8

-beaker
-electrodes (anode and cathode)
-battery

Question 9

what do you call the positive and neagative electrode?

Answer 9

positive - anode
negative - cathode

Question 10

how does electrolysis for lead bromide work?

Answer 10

-the negative bromide ions will be attracted to the positive anode and when they get there they’ll be discharged, which just means that they go from a charged ion to a neutral atom, then they’ll usually float off as a gas.

-Meanwhile the positive lead ions will be attracted to the negative cathode and again be discharged this time to form pure lead which will then fall to the bottom and from a layer of molten lead

Question 11

what is phytoming?

Answer 11

phytomining is when plants are grown on land which contains a metal compound that we want. The plants take in the metal compounds, which are stored in their tissues. The plants then harvested and burned; the ash contains a high concentration of the metal compound.

Question 12

name 3 common acids and their chemical formulas?

Answer 12

H 2 SO 4 - sulfuric acid
HCl - hydrochloric acid
CH 3 COOH - ethanoic acid

Question 13

what is bioleaching?

Answer 13

by leaching is when bacteria is mixed with the metal or, chemical reactions take place which leads to the production of a solution called leachate. The leachate contains a metal compound that we want to extract

Question 14

as temperatue increases, solubility (in water) …

Answer 14

increases

Question 15

what makes a soltion an acid or an alkali?

Answer 15

if it has H+ ions then acid and if it has OH- then alkali

Question 16

on a pH curve what do you call the point where the indicator changes colour?

Answer 16

the end point

Question 17

what do you call it when ther is equal conc. of acid and alkali?

Answer 17

the equivilent point

Question 18

what makes an acid a strong acid or a weak acid?

Answer 18

its a strong acid if all molecules ionise (dissociate to form ions) or a weak acid if not 100% of the molecules ionise.

Question 19

explain why it is possible to have a very dilute solution of a strong acid, with a higher pH value than a concentrated solution of a weak acid.

Answer 19

• pH depends on concentration of H + ions
  -so although weak acid does not ionise completely, it could have a
  higher concentration of H + ions if amount of strong acid per
  decimetres cubed is very ,very small
  -strong acids ionise completely
  -but in very dilutes solution may produce fewer H plus ions in a given
  volume of solution than a concentrated solution of a weak acid

Question 20

give 4 reasons why propanoic acid is descrobed as a weak acid and nitric acid is descriobed as a strogn on.

Answer 20

• Propanoic acid does not ionise completely when added to water
• only a small fraction form H + ions
  -therefore, propanoic acid does not produce a high concentration of H plus ions as a strong acid and equal concentration
• nitric acid is a strong acid, because it’s molecules ionise completely in water+