AQA GCSE Chemistry Year 10: Quantative Chemistry

What are some uses of quantitative analysis?

. Determine the formulae of compunds and equations for reactions

. Determine purity of chemical samples

. Monitor the yield from chemical reactions

What does identifying different types of chemical reaction allow chemists to do?

. Make sense of how different chemicals react together

. Establish patterns

. Make predictions about the behaviour of other chemicals

What do chemical equations allow us to do?

. Provide a means of representing chemical reactions

. Are a key way for chemists to communicate chemical ideas

What does the law of conservation of mass state?

No atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants

. Means chemical reactions can be represented by symbol equations which are balanced in terms of the numbers of atoms of each element involved on both sides of the equation

What is the relative formula mass of a compound?

. Mr (little indexed r, just hard to type)

. Sum of the relative atomic masses of the atoms in the numbers shown in the formula

What is always true about relative formula mass in a balanced chemical equation?

The sum of the relative formula masses of the reactants in the quantities shown equals the sum of the relative formula masses of the products in the quantities shown

Why might some reactions appear to involve a change in mass?

Because a reactant or product is a gas and its mass has not been taken into account

What are chemical amounts measured in?

moles

What is the symbol for the unit mole?

mol

What is the mass of 1 mole of a substance in grams numerically equal to?

Its relative formula mass

What is always true about 1 mol of 2 different substances?

One mole of a substance contains the same number of stated particles, atoms, molecules, or ions as one mole of any other substance

What is the Avogadro constant?

. The number of atoms, molecules, or ions in a mole of a given substance

. Value is 6.02 x 10²³ per mole

How do the number of atoms and molecules in one mole of carbon and one mole of carbon dioxide compare and why?

. Same number of atoms in one mole of carbon as molecules in one mole of carbon dioxide

. Measurements of amounts in moles can apply to atoms, molecules, ions, electrons, formulae, and equations

Why would you use an excess of one reactant in an equation?

To ensure that all of the other reactant is used

What is the limiting reactant?

. The reactant that is completely used up

. Because it limits the amount of products

What is the unit for the concentration of a solution?

. Mass per given volume

. g/dm³

How do you calculate the concentration of a solution?

mass of solute (g) / volume (dm³)

How many cm³ in 1 ml?

1

How many cm³ in 1 dm³?

1,000

Why is it not always possible to obtain the calculated amount of a product?

. The reaction may not go to completion because it is reversible

. Some of the product may be lost when it is separated from the reaction mixture

. Some of the reactants may react in ways different to the expected reaction

What does the yield mean?

The amount of a product obtained

What is the equation for percentage yield?

% yield = mass of product actually made / maximum theoretical mass of product x 100

What is atom economy?

A measure of the amount of starting materials that end up as useful products

Why is atom economy important?

It's important for sustainable development and for economic reasons to use reactions with high atom economy

What is the equation for percentage atom economy?

. Calculated using the balanced equation for the reaction

. relative formula mass of desired product from equation / sum of relative formula masses of all reactants from equation x 100

In what unit is the concentration of a solution measured?

mol/dm³

What can you use the concentration of a solution in mol/dm³ to calculate?

The amount in moles of solute or the mass in grams of solute in a given volume of solution

How can the volumes of acid and alkali which react with each other be measured?

By titration using a suitable indicator

What is true of moles of gases?

. Equal amounts of moles in gases occupy the same volume NOT FINISHED