all these questions I got wrong on my homework today ...I'm trying to find out why and what the correct answers were .. please help
How many grams of solute are required to make a 504 mL solution of copper (I) nitrate with a concentration of 1.3317 M?
before I had help and was told it was 126 g..it didn't work
When 84.2730 grams of solute are used to make a 504 mL solution of copper (I) nitrate, what is the concentration of the solution? I also received help and told it was .9..it also didn't work.
A student mixes 450 mL of water and 116 mL of 7.90 x 10-5 M greenfood dye solution. What is the concentration of this new dilute solution of green food dye?
this question came out negative so I knew it was wrong
I showed you how to work 1 and 2? You must not have followed instructions. For example, I did NOT say the answer to number 2 was 0.9; however, I said it was about 0.9. That means you go through the calculation yourself, work it to more exacting terms, then report the answer to the correct number of significant figures. If you will show yur work on these three I will try and find the error. Also note that I did NOT say the answer to #1 was 126. I said it was ABOUT 126.
To find the answers to these questions, we need to use the formula for concentration:
Concentration (M) = moles of solute / volume of solution (in liters)
Let's break down each question step by step.
1. How many grams of solute are required to make a 504 mL solution of copper (I) nitrate with a concentration of 1.3317 M?
To determine the number of grams of solute needed, we need to consider the molar mass of copper (I) nitrate (CuNO3). The molar mass is calculated by adding up the atomic masses of each element in the compound. In this case, copper (Cu) has a molar mass of 63.55 g/mol, nitrogen (N) has a molar mass of 14.01 g/mol, and oxygen (O) has a molar mass of 16.00 g/mol.
Molar mass of CuNO3 = (63.55 g/mol) + (14.01 g/mol) + 3 x (16.00 g/mol) = 63.55 g/mol + 14.01 g/mol + 48.00 g/mol = 125.56 g/mol
Now, we can use the formula for concentration to find the grams of solute:
Concentration (M) = moles of solute / volume of solution (in liters)
1.3317 M = moles of solute / 0.504 L
Rearranging the equation, we get:
moles of solute = 1.3317 M x 0.504 L = 0.6714036 mol
To convert moles to grams, we need to multiply by the molar mass:
grams of solute = 0.6714036 mol x 125.56 g/mol ≈ 84.30 g
So the correct answer is approximately 84.30 grams of solute, not 126 grams as previously suggested.
2. When 84.2730 grams of solute are used to make a 504 mL solution of copper (I) nitrate, what is the concentration of the solution?
We will use the same molar mass of copper (I) nitrate obtained earlier, which is 125.56 g/mol.
First, we need to convert the volume of the solution to liters:
504 mL = 504 mL ÷ 1000 mL/L = 0.504 L
Next, we can calculate the moles of solute:
moles of solute = (mass of solute) / (molar mass)
= 84.2730 g / 125.56 g/mol
= 0.671331 mol
Finally, we can calculate the concentration:
Concentration (M) = moles of solute / volume of solution (in liters)
= 0.671331 mol / 0.504 L
= 1.33 M
The correct answer is approximately 1.33 M, not 0.9 as previously suggested.
3. A student mixes 450 mL of water and 116 mL of 7.90 x 10^-5 M green food dye solution. What is the concentration of this new dilute solution of green food dye?
In this case, we need to calculate the final volume of the solution by adding the volumes of water and the green food dye solution:
Total volume of solution = volume of water + volume of green food dye solution
= 450 mL + 116 mL = 566 mL
Before calculating the concentration, we need to convert the total volume to liters:
Total volume of solution = 566 mL ÷ 1000 mL/L = 0.566 L
Now we can calculate the moles of green food dye:
moles of solute = (concentration) × (volume of solution)
= (7.90 x 10^-5 M) × (0.566 L)
= 4.47 x 10^-5 mol
Since the total volume includes the volume of water (which does not contain the solute), the concentration of the green food dye needs to be recalculated:
Concentration (M) = moles of solute / volume of solution (in liters, excluding water)
= (4.47 x 10^-5 mol) / (0.450 L)
= 9.94 x 10^-5 M
The correct answer is approximately 9.94 x 10^-5 M, not negative as previously mentioned.