80ml of hcl is added to 2.5gm of pure cac03 when the reaction is over, then 0.5gm cac03 is left. Find the normality of the acid
The answer 0.5N
Who helps step by step
mL x N x m.e.w. = grams.
80 x N x 0.050 = 2.0
grams CaCO3. Started with 2.5, finished with 0.5, used 2.0 g
m.e.w. CaCO3 = 100/2000 = 0.050
To find the normality (N) of the acid, we first need to understand the reaction taking place. In this case, hydrochloric acid (HCl) is reacting with calcium carbonate (CaCO3) to form calcium chloride (CaCl2), water (H2O), and carbon dioxide (CO2).
The balanced chemical equation for this reaction is:
2HCl + CaCO3 -> CaCl2 + H2O + CO2
Given:
- Initial amount of HCl = 80 ml
- Initial amount of CaCO3 = 2.5 g
- Amount of CaCO3 left after the reaction = 0.5 g
Step 1: Convert the mass of CaCO3 to moles.
The molar mass of CaCO3 is 100.09 g/mol (1 calcium atom + 1 carbon atom + 3 oxygen atoms).
Number of moles of CaCO3 = Mass / Molar mass
Number of moles of CaCO3 = 0.5 g / 100.09 g/mol
Number of moles of CaCO3 = 0.0049995 mol (approximately 0.005 mol)
Step 2: Determine the molar ratio between HCl and CaCO3 from the balanced equation.
From the balanced equation, we can see that the molar ratio between HCl and CaCO3 is 2:1. This means that 2 moles of HCl react with 1 mole of CaCO3.
Step 3: Calculate the amount of HCl that reacted.
Since the molar ratio is 2:1, the moles of HCl that reacted is equal to half the moles of CaCO3. This can be calculated as:
Moles of HCl = 0.5 * Number of moles of CaCO3
Moles of HCl = 0.5 * 0.005 mol
Moles of HCl = 0.0025 mol
Step 4: Convert the moles of HCl to normality (N) of the acid.
Normality (N) is defined as the number of equivalent weights of the solute per liter of solution. For hydrochloric acid, the equivalent weight is equal to its molar mass, which is 36.46 g/mol.
Normality (N) = Moles of HCl / Volume of Solution (in liters)
Volume of Solution = 80 ml = 80/1000 = 0.08 L
Normality (N) = (0.0025 mol) / 0.08 L
Normality (N) = 0.03125 N
Therefore, the normality of the acid (HCl) is approximately 0.03125 N. Rounded to two decimal places, it is 0.03 N.