Explain what is meant by relative atomic mass?-
Relative atomic mass is the measure of the mass of an element which consists of the protons and neutrons; it is always the bigger number and has the symbol Ar. An obvious example of this is oxygen has the Ar of 16 yet sodium has the Ar of 23.
Explain how relative formula mass is calculated using the periodic table-
You need to find the relative atomic mass (M) for each atom but this can only be done when the relative atomic mass have been found, then you add all of the masses in the compound together to find the RFM. Sodium Hydroxide is the example we used within our experiment.
Na= 23
O= 16
H= 1
NaOH 23 + 16 + 1 = 40
NaOH Mr= 40
Explain how it is possible to work out amounts of substance
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Explain how the molarity of the standard solution (the alkali) was calculated in the experiment (equation explained)-
0.1M of NaOH is required, this equation will be used:
Concentration = moles volume
This will be rearranged to find the moles needed to carry out the experiment. The concentration of the experiment using NaOH is 0.1M so we just need to rearrange the equation to find the molarity.
0.1 x 0.250 = 0.0250 moles
Number of moles = mass RFM
0.0250 = mass 40
0.0250 x 40 + 1g (mass)
Explain how this enabled you to accurately calculate the molarity of each acid used in the titrations (equations explained)-
Molarity of the acid = molarity of the alkali x volume of the alkali volume of acid
Firstly we will need to add up all of the volumes found within the titration to find an average:
13.10+13.20+13.10= 13.13
Molarity of Ethanoic acid = 0.1 x 25.00 = 0.190 mol dm-3 13.13
Molarity of Hydrochloric acid = 1.0 x 25.00 = 0.077 mol dm-3 32.53