The molar mass of KCl is 74.5 (39+35.5).
This means that a 1molar solution would contain 74.5g KCl per liter.
Therefore, a 3 molar solution would contain 74.5 x 3 = 223.5g KCl per liter.
Now, 1 liter has 1000 ml in it. We need to prepare a 3M solution in 500 ml.
Just simple math here. If 1000ml has 223.5g of KCl in it to make a 3M solution, 500ml will have half the amount (since 500 is the half of 1000).
So, we'll divide 223.5 by 2. This gives us 111.75.
So, first of all you need to weigh out 111.75g of KCl. You do this by first weighing the empty dish on the scale and calibrating the scale to zero with the dish on it. Then add KCl to the dish on the scale until the scale reads 111.75g.
Then, you transfer this amount into a round bottomed flask of volume 500ml. After adding KCl, fill up half the bottle and swirl gently to dissolve the solid. Then, make the volume up till the mark to make up 500ml of solution. Cork the bottle and shake it to mix.
This means that a 1molar solution would contain 74.5g KCl per liter.
Therefore, a 3 molar solution would contain 74.5 x 3 = 223.5g KCl per liter.
Now, 1 liter has 1000 ml in it. We need to prepare a 3M solution in 500 ml.
Just simple math here. If 1000ml has 223.5g of KCl in it to make a 3M solution, 500ml will have half the amount (since 500 is the half of 1000).
So, we'll divide 223.5 by 2. This gives us 111.75.
So, first of all you need to weigh out 111.75g of KCl. You do this by first weighing the empty dish on the scale and calibrating the scale to zero with the dish on it. Then add KCl to the dish on the scale until the scale reads 111.75g.
Then, you transfer this amount into a round bottomed flask of volume 500ml. After adding KCl, fill up half the bottle and swirl gently to dissolve the solid. Then, make the volume up till the mark to make up 500ml of solution. Cork the bottle and shake it to mix.
