In preparing a 1 liter of a 0.9% sodium chloride solution, how many ml of water are needed if using a 15% solution?

To determine how much water is needed to prepare a 1 liter (1000 ml) of a 0.9% sodium chloride solution using a 15% sodium chloride solution, you need to calculate how much of the 15% solution is required and then find out how much water to add.

First, calculate the amount of sodium chloride required for the 0.9% solution in 1 liter:

0.9% of 1000 ml is calculated as:

0.9 g/100 ml × 1000 ml = 9 g of sodium chloride.

Now, using the 15% solution, we need to find how much of this solution contains 9 grams of sodium chloride. A 15% w/v solution means there are 15 grams of sodium chloride in every 100 ml. To find out how many ml of the 15% solution you need to get 9 grams, set up the following proportion:

15 g/100 ml = 9 g/x

Cross-multiply and solve for x:

15g * x = 9g * 100ml

15x = 900

x = 900 ml

So, you will need 900 ml of the 15% sodium chloride solution