2.12 grams of Na2co3 is dissolved in 500 ml of water 20 ml of this the solution is diluted to 2 litres then the final molarity of the solution is....?
Answers
You would need 13.87 g of CaCl₂ to make 250 mL of a 0.5 M solution.
M or molarity refers to the moles per litre of a solution. The first step is to calculate how many moles are in 250 mL of this solution.
The easiest way is to use simple ratios.
0.5 mol1 L=x mol0.25 L (250 mL has been converted to 0.25 L)
To solve, cross multiply.
x mol=0.25 L×0.5 mol1 L = 0.125 mol
Therefore, there is 0.125 mol of CaCl₂ in 250 mL of the solution.
Next, you need to calculate the molar mass of CaCl₂, which can be done by adding the individual molar masses of Ca and Cl (found in most periodic tables of the elements).
Ca = 40.08 g/mol
2 × Cl = 2 ×35.45 g/mol = 70.90 g/mol
CaCl₂ = 110.98 g/mol
Lastly, combine the two prior steps. If there is 110.98 g of CaCl₂ per mole, and 0.125 mol of CaCl₂ in 250 mL of the solution, multiply the quantities.
0.125 mol × 110.98 g/mol = 13.87 g
The above answer is rounded to four significant digits, as the molar masses used in calculation were to four significant digits.
To restate the answer, 13.87 g of CaCl₂ is needed to make 250 mL of a 0.5 M solution.