Description Question: If 10.0 grams of NaCl is dissolved in 100.0 mL of water what is the concentration in weight/volume percent? What is the molarity? Reply: First: the weight/volume percent is 10% the molarity is 0.855molL-1 1. weight by volume percent is given by the formula (w/v)%=(weight of solute in gram /volume of solution in ml) x 100 given weight of solute =10 gram volume of solution=100ml put these values in above formula (w/v)%=(10g/100ml) x 100% (w/v)%=10% so the weight/volume percent is 10% 2. molarity is defined as number of moles of solute dissolved per litre of solution represented by the formula molarity =number of moles/volume of solution in litre firstly we have to find out number of moles of NaCl number of moles are given by the formula number of moles =given mass/molar mass given mass of NaCl=5 gram molar mass of NaCl=58.44gmol-1 so number of moles-=5g/58.44gmol-1 number of moles=0.0855mol so there are 0.0855 mol of NaCl present given volume of solution =100ml convert this inti litre 1litre=1000ml 1ml=1/1000litre 100ml=100/1000=0.1litre put these values in the formula of molarity molarity=0.0855mo/0.1L=0.855molL-1 so the molarity is 0.855molL-1 Second: To calculate the concentration %(mass/volume) and molarity of 10 grams of NaCl that dissolves in 100.0 mL of H2O is done by following these steps: First find the given information – 10g of NaCl 100.0mL of water Next find equation(s) that will be needed – For %(mass/volume): Concentration %(m/v) = Mass(g)/Volume(mL) X 100% Substitute givensè C%(m/v)= 10g/100.0 mL X 100% = 10% (m/v) For molarity: M= moles/volume(L)
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