Commercial hydrazine is sold as a 64% solution. Using that as your starting material, how would you prepare a 5% solution of hydrazine?

well if it is sold as 64% solution would that mean that it has 64g of hydrazine per 100ml of solvent(water)?
and what they want in the end is a 5% solution or 5g hydrazine per 100ml of water?

as for how to do this I'm not sure, mathematically or step wise either.

Thanks

percent weight/weight is, in this case,

64 g hydrazine in 100 g SOLUTION. IF, and only if, the density of that solution is 1.00 can that be 100 mL and then it is 100 mL solution and not 100 mL H2O. Since the density of hydrazine is 1.01, I suspect the density of the solution would be so close to 1 that it wouldn't matter; however, since you aren't give a density I assume you are to work the problem not using mL.
A 64% solution is [64 g N2H4/(64 g N2H4 + 36 g H2O)]*100 = 64%.
Now just change the numbers to what you want.
[64 g N2H4/(64 g N2H4 + y g H2O}]*100 = 5% and solve for y g H2O. Then y gH2O + 64 g = total grams of solution.
So you start with 100 g solution(64 g hydrazine) and dilute with water to 1280 g solution and you have a BUNCH of 5% solution. The problem makes it easier by not specifying how much solution is to be prepared. If you don't want that much just divide by an appropriate number to obtain a more manageable quantity. Check my thinking.

I have to go out but I'll check and repost if I don't understand.

Thanks Dr.Bob

An ammonia solution is made by diluting 0.150L of the concentrated commercial reagent until the final volume reaches 1.00L.

Yes, you are correct. A 64% solution means it contains 64 grams of hydrazine per 100 mL of solvent (usually water). And you are also correct that they want a 5% solution, which would mean 5 grams of hydrazine per 100 mL of water.

To prepare a 5% solution of hydrazine from the 64% solution, you will need to dilute the concentrated solution with water. Here's how you can do it step by step:

1. Determine the volume of the 64% solution you need to prepare. Let's assume you want to make 500 mL of the 5% solution.

2. Calculate the amount of hydrazine needed in the final solution. Since you want a 5% hydrazine concentration, it means you need 5 grams of hydrazine per 100 mL. Therefore, for 500 mL, you will need (5 g/100 mL) x 500 mL = 25 grams of hydrazine.

3. Now, set up a proportion to calculate the volume of the 64% solution needed. The proportion should be:

(Volume of 64% solution) / (Volume of water added) = (Concentration of 64% solution) / (Concentration of desired solution)

Let's denote the volume of the 64% solution as V1 and the volume of water added as V2. The concentration of the 64% solution is 64% or 64 g/100 mL, and the concentration of the desired 5% solution is 5 g/100 mL. Plugging in these values, the proportion becomes:

V1 / V2 = (64 g/100 mL) / (5 g/100 mL)

Simplifying the equation, we get:

V1 / V2 = 12.8

4. Rearrange the equation to solve for V2:

V2 = V1 / 12.8

5. Substitute the volume of the 64% solution you need (500 mL) into the equation to find V2:

V2 = 500 mL / 12.8 ≈ 39 mL

Therefore, you will need to add 39 mL of the 64% hydrazine solution to your final solution.

6. Finally, add 39 mL of the 64% hydrazine solution to a container and then add enough water to bring the total volume up to 500 mL. This will give you a 5% hydrazine solution.

It's important to note that handling hydrazine can be hazardous, so appropriate safety precautions should be taken when working with it.