How would you prepare 455 g of aqueous solution that is 6.50% sodium sulfate Na2SO4 by mass?
percent by mass = grams/100 g solution.
X grams/455 = 0.065
solve for X. Subtract 455-X to calculate how much water must be added.
ok i got -454.935 is this right
No.
(X/455) = 0.065
X = 455*0.065 = ??
Grams water = 455 - ?? = xx
Then check yourself.
(??/455)*100 = 6.5%
Does it make sense to you that you can subtract 454.935 g from 455 g to make a 6.5% solution? What's X? X is the amount of Na2SO4 that must be added to some water to make the 6.5% solution of Na2SO4.
so then i did it wrong... :( is it 142g for the Na2SO4 that needs to be put into there
29.575/455*100=6.5%
Yay :)
I would round the 29.575 g Na2SO4 to to 29.6 grams. Remember the question. The question was how to prepare 455 g of a solution that was 6.5% Na2SO4. That answer is to dissolve 29.6 g Na2SO4 in 455-29.6 g water (which would make a total of 455 g).
Well, I gotta say, that's one way to look at it! But seriously, let's break it down. You have 455 grams of solution that is 6.50% sodium sulfate by mass. To find how many grams of sodium sulfate you have, you multiply the mass of the solution by the percent by mass: 455 g * 0.065 = 29.575 g. So, you have approximately 29.575 grams of sodium sulfate. Now, to find how much water you need to add, you subtract the mass of the sodium sulfate from the total mass: 455 g - 29.575 g = 425.425 g. So, you'll need about 425.425 grams of water to make the solution. Keep in mind, though, that these calculations are based on the assumption that the density of the solution is equal to the density of water. If it's different, the actual masses might vary a bit. But hey, at least you tried!
To prepare a 455 g solution that is 6.50% sodium sulfate (Na2SO4) by mass, you can follow these steps:
1. Set up the equation using the given information: percent by mass = grams/100 g solution.
6.50% = X grams/100 g
2. Solve the equation for X by cross-multiplying:
X grams = (6.50/100) * 100 g
X grams = 6.50 g
3. Subtract X from 455 g to figure out how much water needs to be added:
Water grams = 455 g - X grams
Water grams = 455 g - 6.50 g
Water grams = 448.50 g
So, to prepare 455 g of a 6.50% sodium sulfate solution, you would need to dissolve 6.50 g of Na2SO4 in 448.50 g of water.