Acids, Bases and Salts Flashcards
Why is Litmus paper not very accurate
Litmus paper is not very accurate as it cannot differentiate between strong and weak. Also, red litmus paper does not distinguish between acid and neutral. Blue litmus does not distinguish between alkali and neutral.
Why is universal indicator a better indicator
Universal indicator is more accurate as it distinguishes between strong and weak
How is universal indicator tested
Universal indicator can either be used as a solution that is dropped into the substance being tested. Or as a paper that is dipped into the substance being tested. The colour that the substance turns is then compared with the pH colour chart, to determine a number value of pH
What is the best way to measure pH
The best way to measure pH with a pH meter It measures pH to at least one decimal place in the solution and the digital reading is recorded to one decimal place The pH meter is placed
Give a solution for pH 0-2 strong acid
Nitric acid
Hydrochloric acid
Sulfuric acid
Give a solution for pH 3-6 weak acid
vinier
ethanoic acid
carbonic acid
Give a solution for pH 7 neutral
water
sodium nitrate
sodium chloride
Give a solution for pH 8-11 weak alkali
ammonia
Give a solution for pH 12-14 strong alkali
sodium hydroxide
What is an Acid
An acid is a substance that dissolves in water producing hydrogen ions (H+(aq))
What is an Alkali
An alkali is a substance that dissolves in water producing hydroxide ions (OH-(aq))
What’s the difference between strong and weak acids
strong acids are acids that are completely ionised in water and weak acids are acids that are partially ionised in water
What’s the difference between strong and weak alkali
strong alkali are alkali that are completely ionised in water and weak alkali are alkali that are partially ionised in water
What’s the difference between diluted and concentrated solutions
A concentrated solutions contains a large number of acid particles dissolved per unit volume. A diluted solutions contains a small number of acid particles dissolved per unit volume
What is a base
A base is a substance that can neutralize the acid by reacting with hydrogen ions. Most bases are minerals that react with acids to form water and salts.
What is neutralisation
neutralisation is a chemical reaction in which acid and a base react with an equivalent quantity of each other. In a reaction in water, neutralization results in there being no excess of hydrogen or hydroxide ions present in the solution.
What is the neutralisation equation
H+(aq) + OH-(aq) → H2O(l)
What is all the neutralisation word equations
- Acid + Alkali → Salt + Water
- Metal + Acid →Salt + Hydrogen
- Metal Carbonate + Acid →Salt + Water + Carbon-Dioxide or Metal Hydrogen carbonate + Acid →Salt + Water + Carbon-Dioxide
- Acid + Ammonia →Ammonia Salt
What are the 4 important salt
Nitric acid (HNO₃) nitrate
Hydrochloric acid (HCl) chloride
Sulfuric acid (H₂SO₄) sulfate
Ammonia (NH3) ammonium
What does an exothermic reaction mean
An exothermic is one which heat is given out
Are neutralisation reactions exothermic
YES
Step by step for what is happening during a endothermic neutralisation reactions
If you added an acid and an alkali together in a beaker, with a thermometer. You would see the temperature rising an the thermometer and feel the beaker warming up.
Why is a polystyrene cup used instead of a beaker in the neutralisation reactions
because a polystyrene cup is an insulator
How can hydrogen be tested
Apply a lighted splint
A popping sound result
How can carbon dioxide be tested
Bubble the gas into colourless limewater (calcium hydroxide solution)
The solution will change to milky if the gas is carbon dioxide
What are some observations for acid reactions
- If a gas is produced the observation is ‘bubbling’
-If a solid (such as a solid metal, base or carbonate) reacts with the acid then the observation is ‘solid disappears and a solution is produced’
-Most acid reactions are exothermic (heat given out) the observation is ‘heat released’. Two exceptions to this: are reactions with copper(II) oxide and sodium hydrogen carbonate
Colour observations for Copper(II) Oxide
Black solid
Colour observations for Copper(II) Carbonate
Green solid
Colour observations for Hydrated Copper(II) Sulfate
Blue crystals
Colour observations for salts in solutions
Blue solutions
Colour observations for group 1, group 2, aluminium and zinc compounds
White solids
give a colourless solution when dissolved
Observations you need for your answer for Acid and Metal
Bubbles, Heat is released, Solid disappears and Colourless solution formed
Observations you need for your answer for Acid and Copper carbonate
Bubbles, Heat is released, Solid disappears and Blue solution formed
Observations you need for your answer for Acid and Sodium Carbonate
Bubbles, Heat is released, Solid disappears and Colourless solution formed
