Question

To prepare 20 mL of 15 mM NaCl, how much NaCl would you need to weigh?
2. To prepare 5 mL of 1 mM glucose, how much glucose would you need to weigh? How do you prepare
1 mL of 1 mM NaCl using the NaCl solution you prepared in (1)?
3. How do you prepare 1 mL of 10 µM glucose using the glucose solution you prepared in (2)?
So repost I am not sure if I am doing any of these right

Answer 1

Go with the definition. 1M means 1 mol in 1 L of solution. So for #1, 15 mM is 0.015M so you want 0.015 mols in 1L. You only want 20 mL so you want
0.015 mols x (20 mL/1000 mL) = ? mols NaCl.
mols NaCl = grams NaCl/molar mass NaCl. You know mols and molar mass, solve for grams NaCl.

Answer 2

I get that. but what about how would you prepare 1mL of 1 mM NaCl using the NaCl solution you prepared in part 1?

Answer 3

You know the first one is 0.015. You want to dilute it to 0.01M. You want 1 mL of the 0.01 so
0.015 x mL = 0.01 x 1 and solve for mL of the 0.015. You may need a micropipet OR you can make up solutions and make serial dilutions.

Answer 4

1M is not mole , its Molarity or amount of concentration .
please check on the definition once more .