first task is to prepare 250 ml of 3 M glucose. Then You are preparing a solution and the recipe calls for 25 ml of 10% glucose. How much of the 3M glucose stock would you need to add to so that you are adding the same molar amount of glucose?

You make 3M glucose with 135 g glucose in 250 mL soln. (Check it: That is (135/180) x (1/0.250) = 3 M

25 mL of a 10% soln is how many grams. That is 10g x (25/100) = 2.5 g glucose.

So the question is how much of the 3M stuff to take to obtain 2.5g. That is
250 mL x (2.5/135) = 4.62 mL.
Check my work.

To find out how much of the 3M glucose stock you would need to add to get the same molar amount of glucose in 25 ml of 10% glucose solution, we can use the concept of molarity and the formula:

Molarity = Moles of solute / Volume of solution (in liters)

First, let's calculate the moles of glucose in 25 ml of 10% glucose solution:

Step 1: Convert the volume to liters
25 ml = 25 / 1000 = 0.025 L

Step 2: Calculate the moles of glucose using the molarity formula
Molarity = Moles of glucose / Volume of solution
10% glucose solution means the concentration is 10 g/100 ml.
So, the mass of glucose in 0.025 L of 10% glucose solution is 10 g.

To calculate moles, we need the molar mass of glucose. Its chemical formula is C6H12O6, which means it has a molar mass of 180.16 g/mol.

Moles of glucose = Mass of glucose / Molar mass
Moles of glucose = 10 g / 180.16 g/mol

Step 3: Calculate the molar amount of glucose in 25 ml of 10% glucose solution
Molar amount of glucose = Moles of glucose / Volume of solution
Molar amount of glucose = (10 g / 180.16 g/mol) / 0.025 L

Now, we need to determine how much of the 3M glucose stock is required to have the same molar amount of glucose.

Step 4: Calculate the volume of the 3M glucose solution needed
Molarity = Moles of glucose / Volume of solution
3M = Moles of glucose / Volume of 3M glucose solution

Rearranging the formula, Volume of 3M glucose solution = Moles of glucose / 3M

Step 5: Substitute the value of moles from step 3 into the formula
Volume of 3M glucose solution = (10 g / 180.16 g/mol) / 3 M

Finally, calculate the volume of the 3M glucose solution needed:

Volume of 3M glucose solution = (10 / 180.16) / 3 L
Volume of 3M glucose solution ≈ 0.018 L or 18 ml (rounded to the nearest milliliter)

Therefore, you would need to add approximately 18 ml of the 3M glucose stock to have the same molar amount of glucose as in 25 ml of 10% glucose solution.