Question

Suppose the Chemist weighs out a 5.931g sample of the standard sodium chloride (formula Weight 58.44) and dissolves it in water to make exactly one litre of solution. what is the actual mass of the sodium chloride in the sample.

please help its due in 2 hrs

Answer 1

Both molarity and formality express concentration as moles of solute per liter of solution. Molarity is the concentration of a particular chemical species in solution whereas formality, is a substance’s total concentration in solution irrespective to its specific chemical form.

For substances that ionize in solution, such as NaCl, molarity and formality are different. For example, dissolving 0.1 mol of NaCl in 1 L of water gives a solution containing 0.1 mol of Na⁺and 0.1 mol of Cl^–. The molarity of NaCl, therefore, is zero since there is essentially no undissociated NaCl in solution.

Now, formula weight of NaCl is 58.44 g

Here, it seems like the chemist want to prepare 0.1(F) solution of NaCl by dissolving 5.931 g of NaCl in water to make a exactly 1L solution .

However, theoritically if sample of NaCl is 100% pure then chemist should use 5.844 g of standard NaCl

So it is evident that purity of sample of standard NaCl is less than 100 % and it's purity is = (5.844/ 5.931 ) x100

= 98.5 % (ANSWER)