Final answer:
To prepare a 200 ml solution with a concentration of 5% w/v of salt, you need to use 10 grams of sodium chloride.
Step-by-step explanation:
To determine how much salt (sodium chloride, NaCl) is needed to prepare 200 ml of a 5% (w/v) solution, we start by understanding that 5% (w/v) means 5 grams of salt per 100 ml of solution. Since we want to prepare 200 ml, we need to calculate the mass of solute that corresponds to 200 ml of solution:
- (5 g of NaCl is to 100 ml solution) as (x g of NaCl is to 200 ml solution).
By setting up a proportion, we find:
5 g / 100 ml = x g / 200 ml
Now we cross multiply and solve for x:
(5 g) * (200 ml) = x g * (100 ml)
1000 g*ml = x g * 100 ml
x = 1000 g*ml / 100 ml
x = 10 g
Therefore, to prepare 200 ml of a 5% (w/v) salt solution, you need 10 grams of sodium chloride.