Acids and bases

Question 1

identify acids and bases as common gorups of chemicals and give ezamples of acids and bases used in the everyday. - acids.

Answer 1

Acids
- substances that can donate protons and gace a sour taste
- often reacts to form salts and water
e.g. vinegar-Acetic acid lemon juice (citric acid) used in cleaning supplies.

Question 2

identify acids and bases as common gorups of chemicals and give ezamples of acids and bases used in the everyday. - bases

Answer 2

Bases
- substances that can accept protons and donate hydroxide ions.
- baking soda- sodium bicarbonate- lye - sodium hydroxide- used in cleaning and operations.

Question 3

recall some properties of acids and bases and that they can be distinguished using an indicator. - acids

Answer 3

Acids
- corrosive
- sour taste
- reacts with some metals to form hydrogen gas and salt.
- conducts electricity
- neutralised by bases to form water and salt

Question 4

recall some properties of acids and bases and that they can be distinguished using an indicator. - bases

Answer 4

Bases
- caustic
- bitter taste
- conducts electricity
- neutralised by acids to form water and salt.

Question 5

recall some properties of acids and bases and that they can be distinguished using an indicator. - indicators.

Answer 5

Indicators: chemicals that change colour depending on the concentration of particular ions in a solution
- numerous indicators respond to acids and bases by changing colours over a range of pH values.
- universal indicator: muzture of several indicators so that it changes colour over a wide range of pH values.

Question 6

use a range of common indicators to determine if a substance is acidic, basic or neutral. - acidic.

Answer 6

• dissolves in water to produce solutions that turn litmus paper red.
• pH of less than 7
• universal indicator: red or orange.
• tastes sour
• conducts electricity
• reacts with a base removing the bases properties.

Question 7

use a range of common indicators to determine if a substance is acidic, basic or neutral. - basic.

Answer 7

• dissolves in water to create a solution that turns litmus paper blue.
• conducts electricity
• has a bitter taste
  0 reacts with acid to remove its acidic properties.

Question 8

use a range of common indicators to determine if a substance is acidic, basic or neutral. - neutral.

Answer 8

• pH of exactly 7.
• universal indicator = green
• litmus paper stays the same colour
• no reactions with acids or bases.

Question 9

Outlien the diffrence between concentrated and dilute acid vs strong and weak acid- concentrated and dilute.

Answer 9

concentrated
- a lot of solute per unit of solvent.
dilute
- very little solute per unit of solvent.

Concentration refers to the amount of acid in a given volume of solution, affecting reactivity and corrosiveness.

Question 10

Outlien the diffrence between concentrated and dilute acid vs strong and weak acid- strong and weak

Answer 10

strong
- most of its moldecules release hydrogen ions into the solution
weak
only a few molecules release hydrogen ions.

Strength refers to the degree of ionization in water, influencing the acid’s ability to donate protons (H⁺ ions).

Question 11

recall the pop test for hydrogen using a lit splint or match.

Answer 11

• acid + metal –> salt + hydrogen gas.
  so - hydrochloric acid + magnesium –> magnesium chloride + hydrogen gas.
• hydrogen gas burns with a clear hot flame to form water.
• when flame/spark is put in the hydrogen gas there is a pop sound.
  1- quater fill large test tube with hydrchloric aci
  2- small piece of magnesium ribbon
  3- trap the gas formed by reaction in a test tube
  4- magnesium finished the reaction insert a lit match into the mouth of the larger test tube.

Question 12

recall the limewater test for carbon dioxide.

Answer 12

• acid + carbonate –> salt + water + carbon dioxide gas.
• hydrochloric acid + calcium carbonate –> calcium chloride + water + carbon dioxide.
• to test for carbon dioxide limewater is used when carbon dioxide is bubble through the limewater, the limewater changes from clear and colourless to cloudy and white.

1- half filled tube with limewater
2- attach tube to side-arm test tube, place the end of the tube into the limewater
3- 2cm hydrochloric acid and small aount of calcium carbonate into the side arm with a stopper on top of the tuble.

Question 13

Outline the substances are formed during chemical reactions by rearranging atoms rather than creating or destroying them. - conservation of mass.

Answer 13

conservation of mass.
- atoms are neither created or destroued during chemical reations and the total mass is the same.
- reactans transform into products.

Question 14

Outline the substances are formed during chemical reactions by rearranging atoms rather than creating or destroying them rearrangement of atoms.

Answer 14

rearrangement of atoms.
- during a reaction the beond between atomis in reactants are broken and new bonds form to create new products.

e.g. combustion : hydrocarbons react with oxygen and rearrange into carbon dioxide + water.

Question 15

conduct neutralisiation reactions using hydroxides + carbonates and discuss their comparative risks.- neutralisiation with hydroxides.

Answer 15

e.g. Hydrocholric acid + sodium hydroxide –> sodium chloride + water.
- corrosive: many are highly cuastic and can result in severe burns.
-reactivity:can react vigorously with acids ausing heat and potential splattering.

Question 16

conduct neutralisiation reactions using hydroxides + carbonates and discuss their comparative risks. neutralisation with carbonates.

Answer 16

e.gHydrochloric Acid + Sodium Carbonate → Sodium Chloride + Water + Carbon Dioxide
- lowe reactivity: reacts more slowly with acids to often produce carbon dioxide which can bubble and fizz.
- less corrosive: less corrosive than hydroxide which means a lower burn risk.
- gas production: evolution of carbon dioxide can cause a pressure build up in a sealed container.

Question 17

Use the pH scale to determine the acidity of.a range of substances.

Answer 17

• acids and bases use the pH scale- the potential of hydrogen scale.
• pH scale: a logorithmic scale of hydrogen ion concentration 0-14

Question 18

Use the pH scale to determine the acidity of.a range of substances.- acids

Answer 18

num below 7 is an acid has higher concentration of hydrogen atoms than hydroxide atoms.

Question 19

Use the pH scale to determine the acidity of.a range of substances.- bases

Answer 19

num. above 7 which is basic, has a higher concentration of hydroxide ions tha hydrogen ions.

Question 20

Use the pH scale to determine the acidity of.a range of substances- neutral.

Answer 20

num is 7
pure water is 10 to the -7.

Question 21

construct word equations to represent reactions ( mostly acids)

Answer 21

Substance a + substance b –> substance c + substance d.
reactants –> product.

Question 22

identify some examples of important chemical reactions in living things.

Answer 22

cellular respiration.
Glucose + Oxygen → Carbon Dioxide + Water + Energy
Converts glucose into ATP, the energy currency for cellular functions.

photosynthesis
Carbon Dioxide + Water + Light Energy → Glucose + Oxygen
Converts light energy into chemical energy stored in glucose.

combustion of fuels.
Fuel + Oxygen → Carbon Dioxide + Water + Energy
Understanding combustion is essential for energy production, environmental science, and improving combustion efficiency to reduce pollution.