Page 127 - Knowledge Organiser Yr8 24-25

Knowledge Base: Science 8.2 Acids and Alkalis Year 8
1. What is an acid and an alkali?
1.1
What is the pH scale?
It is a number scale which shows how acidic or alkaline a solution is.
1.2
What is the pH of a neutral solution (neither acidic or alkaline)?
pH 7.
1. What is an acid and an alkali?
1.14
Can you determine the pH of a solid?
No, pH can only be measured for water based solutions.
1.15
What is the word used to describe water based solutions?
Aqueous.
1.16
Do soaps and cleaning products tend to be acidic or alkaline?
Alkaline.
1.17
Estimate the pH of the following solutions and whether they are acidic or alkaline:
Blood / Bleach / Tomato / Stomach acid / Milk / Soap
Blood – pH 8 (slightly alkaline) Bleach – pH 12 (alkaline) Tomato – pH 4 (slightly acidic) Stomach acid – pH1 (very acidic) Milk – pH 6 (slightly acidic)
Soap – pH 8-10 (alkaline)
1.3 What is the pH of an acidic solution? pH less than 7.
1.4
What is the pH of an alkaline solution?
pH more than 7.
1.5
If a solution had a pH of 6 would it be acidic or alkaline?
Acidic.
1.6
Which is more alkaline: a solution with a pH of 9 or 12?
pH 12.
1.7
Give two ways of determining the pH of a solution.
Using an indicator or a pH meter.
1.8
What colour does litmus paper go in acid solutions?
Red.
1.9
What colour does litmus paper go in alkali solutions?
Blue.
1.10
Describe the colour change with universal indicator as you move up the pH scale.
1.11
A solution turns orange with universal indicator. Is it an acid
or an alkaline and what is it’s pH?
Acid with pH 4.
1.12
What colour would a neutral solution turn with universal indicator?
Green.
1.13
What is the advantage of using universal indicator over litmus paper?
Universal indicator can show us how strongly acidic or alkaline a solution is, not just that the solution is acidic or alkaline.
2. Making Indicators
2.1
Name the 3 common laboratory acids and give their chemical symbols.
Hydrochloric Acid (HCl), Sulfuric Acid (H2SO4), Nitric Acid (HNO3).
2.2
Name a common laboratory alkaline and give its symbol.
Sodium Hydroxide (NaOH).
2.3
Which vegetable can you make an indicator from and what colour does it go in acid and alkali?
Red cabbage indicator goes red in acid and yellow in alkaline.
3. How can we neutralise an acid?
3.1
True or False: A chemical reaction happens when you mix an acid and an alkali.
True.
3.2
What is the chemical reaction between an acid and an alkali called?
A neutralisation reaction.
3.3 How can you neutralise an acid? React it with an alkali.
3.4 How can you neutralise an alkali? React it with an acid.
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