Calculate the molarity of the following solutions:
5.0g of KOH in 4.0L of KOH solution
I went from grams of KOH to moles of KOH to molarity but still got the wrong answer... 5.0g KOH X 1 mol KOH/56.108g KOH = 5.0 mol KOH/56.108=0.0891 mol KOH/4.0L and got the answer of 0.02 M i can't figure out where I went wrong??
From your post you must be plugging the answer into a database of answers. I think the problem is that you are not watching the significant figures.
5.0 has two but your answer of 0.02 has only 1.
Your right i figured it out it was due to the sig figs
Well, it seems you've made a tiny clown-sized boo-boo there! Let's see if we can figure out where things went wrong. You started off correctly by converting grams of KOH to moles of KOH. However, I think you might have made a mistake when calculating the number of moles of KOH.
5.0g KOH times 1 mol KOH/56.108g KOH actually equals approximately 0.0891 mol KOH. So far, so good! However, when dividing by the volume of the solution, you made an error.
0.0891 mol KOH divided by 4.0L of solution gives us approximately 0.0223 M, not 0.02 M.
So, it looks like the final answer is approximately 0.0223 M. Don't worry, math can be tricky sometimes, even for clowns like me!
To calculate the molarity of a solution, you need to divide the number of moles of solute (KOH in this case) by the volume of the solution in liters. Your calculations for finding the moles of KOH are correct, so let's proceed with that.
5.0 g KOH x (1 mol KOH / 56.108 g KOH) = 0.0891 mol KOH
Now, let's calculate the molarity.
Molarity = moles of solute / volume of solution (in liters)
Molarity = 0.0891 mol KOH / 4.0 L
Molarity = 0.022275 M or approximately 0.02 M (rounded to two decimal places)
It appears that you made a calculation mistake when dividing the moles of KOH by the volume of the solution. Double-check your division and try the calculation again.
To calculate the molarity (M) of a solution, you need to divide the number of moles of solute by the volume of the solution in liters. Let's follow your calculation step-by-step to see where the mistake might have occurred.
1. You correctly converted the mass of KOH from grams to moles using the molar mass of KOH (56.108 g/mol):
5.0 g KOH × (1 mol KOH/56.108 g KOH) = 0.0891 mol KOH
So far, your calculation is correct. You have obtained 0.0891 moles of KOH.
2. Next, you divided the moles of KOH by the volume of the KOH solution (4.0 L):
0.0891 mol KOH / 4.0 L = 0.0223 M
It seems like you made a mistake in the division. Let's correct it:
0.0891 mol KOH / 4.0 L = 0.022275 M
Therefore, the molarity of the KOH solution is approximately 0.0223 M.
In this case, the error might have occurred when rounding the result. Always make sure to round to the correct number of significant figures.