Pharmacists sell tablets containing magnesium hydroxide, Mg(OH)2, to combat indigestion. A student carried out an investigation to find the percentage by mass of Mg(OH)2 in an
indigestion tablet. The student reacted the tablet with dilute hydrochloric acid. Mg(OH)2(s) + 2HCl(aq) MgCl2(aq) + 2H2O(l)
The student found that 32.00 cm3 of 0.500 mol dm–3 HCl was needed to react with the Mg(OH)
in a 500mg tablet. [1g = 1000mg].
(i) Calculate the amount, in mol, of HCl used.
mols HCl = M x L = ? = 0.500M x 0.03200 = ?
To calculate the amount in moles of HCl used, we need to use the equation:
moles = concentration x volume
Given:
Concentration of HCl = 0.500 mol dm^3
Volume of HCl = 32.00 cm^3
First, we need to convert the volume from cm^3 to dm^3:
32.00 cm^3 = 32.00 / 1000 dm^3 = 0.032 dm^3
Now we can calculate the amount of HCl used in moles:
moles = 0.500 mol dm^3 x 0.032 dm^3 = 0.016 mol
Therefore, the amount of HCl used is 0.016 mol.
To calculate the amount of HCl used in mol, we can use the following formula:
Amount (mol) = Concentration (mol/dm³) × Volume (dm³)
In this case, the concentration of HCl is given as 0.500 mol/dm³, and the volume is given as 32.00 cm³. However, the volume should be converted to dm³ to be consistent with the concentration unit.
There are 1000 cm³ in 1 dm³, so we can convert the volume as follows:
Volume (dm³) = 32.00 cm³ / 1000 = 0.032 dm³
Now, we can calculate the amount of HCl used:
Amount (mol) = 0.500 mol/dm³ × 0.032 dm³ = 0.016 mol
Therefore, the amount of HCl used in the reaction is 0.016 mol.