Topic 3- Quantitative chemistry

Question 1

What is the law of conservation of mass

Answer 1

the law of conservation of mass states that no atoms are lost or made during chemical reaction so the mass of the products equals the mass of the reactants

Question 2

define relative atomic mass and relative formula mass

Answer 2

RAM- average mass of atoms in an element taking into account masses and abundance of its isotopes, relative to 12C
RFM- sum of RAM’s of all atoms in the formula

Question 3

What is Avogadro’s constant?

Answer 3

the number of atoms, molecules or ions in a mole of a given substance. The value of the constant is 6.02 x 10^23

Question 4

What is the formula that links mass, molecular mass and moles together

Answer 4

mass= mr x moles

Question 5

State what we mean by a limiting reactants in a chemical reaction

Answer 5

In a chemical reaction involving two reactants, its common to use an excess of one of the reactants to ensure that all the other reactant is used. The reactant that is completely used up is called the limiting reactant because it limits the amount of products

Question 6

Write down the two formulae that link concentration, mass and volume together.

Answer 6

Concentration (g per dm^3) = mass (g)/volume (dm^3)
Concentration (mol per dm^3)= nr of moles/volume (dm^3)

Question 7

What is the molar volume of a gas at room temperature and pressure?

Answer 7

1 mole of a gas at room temperature and pressure occupies 24 dm^3

Question 8

what is titration?

Answer 8

a technique for finding the concentration of a solution by reacting a known volume of this solution with a solution of known concentration