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Flashcards in Chemical Changes Deck (16)
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1
Q

The pH scale is a measure of

A

How acidic or alkaline a solution is

2
Q

The lower the pH of a solution…

A

The more acidic it is

3
Q

The higher the pH of a solution

A

The more alkaline it is.

4
Q

A neutral substance has

A

pH 7

5
Q

What is an indicator?

A

An indicator is a due that changes colour depending on whether it’s about or below a certain pH

6
Q

Some indicators contain

A

A mixture of dyes that mean they gradually change colour over a broad range of pH. These are called WIDE RANGE INDICATORS

7
Q

What are wide range indicators useful for?

A

Estimating the pH of a solution

8
Q

How can you electrically measure pH?

A

A pH probe attached to a pH meter can also be used to measure pH electronically

9
Q

How to measure the pH of a solution using a pH probe?

A

The probe is placed in the solution you are measuring and the pH is given on a digital display as a numerical value meaning it’s more accurate than an indicator.

10
Q

Acids and bases

A

Neutralise each other

11
Q

An acid is a substance that

A

Forms aqueous solutions with a pH of less than 7. Acids form H+ ions in water.

12
Q

What is a base?

A

A base is a substance with a pH greater than 7

13
Q

What is an alkali?

A

An alkali is a base that dissolves in water to form a solution with a pH greater than 7. Alkalis form OH- ions in water.

14
Q

Give the name and formula between acids and bases:

A

Neutralisation

Acid + base —> salt + water

15
Q

Neutralisation between acids and alkaline:

A

H+(aq) + OH-(aq) —> H2O(l)

16
Q

When an acid neutralises a base or vice versa, the products are

A

Neutral