A technique in volumetric analysis that is used to find the exact volumes of solutions that react with each other.

The volume of titrant needed to reach the end point in a titration.

Readings within a certain range. For titrations, these usually need to be within 0.10 cm³ of each other.

The number placed in front of a chemical formula to balance an equation; it shows the ratio of substances in a reaction.

1 mole contains 6.02 × 10²³ particles. The mass of a mole of a substance is its relative mass expressed in grams.

Titrations: calculating an unknown concentration

Chemistry

In the Electrolysis unit, pupils will build on their understanding of chemical reactions to explore the process of electrolysis and its applications.

In the Acids and Bases unit, pupils learned about the properties of acids, bases, and alkalis, and the reactions between them to form salts and water.

Making salts

A technique to find exact volumes of reacting solutions.

The volume of titrant needed to reach the end point.

Readings within ±0.10 cm³ of each other.

A number showing the ratio of substances in a reaction.

1 mole contains 6.02 × 10²³ particles.

Match the following key words to their definition.

They ensure the solution has been accurately neutralised.

They allow chemists to calculate a precise average volume.

They help determine the end point of the titration.

What is the stoichiometric ratio of HCl to NaOH in the balanced equation below?
HCl + NaOH → NaCl + H₂O

Calculate the number of moles in 18.5 g of NaOH (relative formula mass = 40).

In a titration, 20 cm³ of 0.5 mol/dm³ HCl neutralises 40 cm³ of NaOH. The balanced equation is:
HCl + NaOH → NaCl + H₂O
What is the concentration of the NaOH?

In a titration, 25 cm³ of 0.4 mol/dm³ H₂SO₄ neutralises 75 cm³ of KOH. The balanced equation is:
H₂SO₄ + 2KOH → K₂SO₄ + 2H₂O
What is the concentration of the KOH in mol/dm³ to 3 d.p.?

A unit of mass for small objects like atoms.

The amount of substance containing Avogadro’s number of particles.

The volume of gas under standard conditions.

The concentration of a solution in mol/dm³.

number of moles = mass × relative formula mass

number of moles = mass ÷ relative formula mass

number of moles = mass + relative formula mass

number of moles = mass – relative formula mass

How do you calculate the number of moles from mass?

Calculate the number of moles in 50 g of NaCl (relative formula mass of NaCl = 58.5).

concentration = number of moles ÷ volume (in cm³)

concentration = number of moles × volume (in cm³)

concentration = number of moles × volume (in dm³)

concentration = number of moles ÷ volume (in dm³)

How do you calculate concentration in mol/dm³?

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