(I need help with these two questions. I don’t know how to solve it.)
1. A student takes 215mL of a 5.0M HCI solution and places it into a beaker. The students then adds enough water to the beaker to make 750mL. Calculator molarity of this new solution.
2. A student starts with a titration by placing 30.0mL of 0.25M NaOH into a flask with 3 drops of phenolphthalein. The student then titrated to the endpoint using 18.0mL of HCI. Calculator concentration (molarity) of the HCI that the student used
1.
5.0 M x [215/750] = ?
2.
NaOH + HCl ==> NaCl + H2O
mols NaOH = M x L = ?
The equation is 1 mol HCl to 1 mol NaOH; therefore,
mols HCl = mols NaOH
Then M HCl = mols HCl/L HCl = ?
1) 1.43?
I’m confused on number #2
Sure, I can help you solve these two questions. Let's start with question 1.
1. To calculate the molarity of the new solution, we need to use the equation:
M1V1 = M2V2
M1 is the initial molarity, V1 is the initial volume, M2 is the final molarity, and V2 is the final volume.
In this case, the initial molarity (M1) is 5.0M, and the initial volume (V1) is 215mL. The final volume (V2) is 750mL.
To find the final molarity (M2), we rearrange the equation:
M2 = (M1 * V1) / V2
Plugging in the values, we get:
M2 = (5.0M * 215mL) / 750mL
M2 = 1.4286M
So, the molarity of the new solution is 1.4286M.
Now, let's move on to question 2.
2. To calculate the concentration (molarity) of the HCl solution used in the titration, we can use the equation:
M1V1 = M2V2
M1 is the concentration of the NaOH solution, V1 is the volume of the NaOH solution, M2 is the concentration of the HCl solution, and V2 is the volume of the HCl solution.
In this case, the concentration of the NaOH solution (M1) is 0.25M, and the volume of the NaOH solution (V1) is 30.0mL. The volume of the HCl solution (V2) is 18.0mL.
To find the concentration of the HCl solution (M2), we rearrange the equation:
M2 = (M1 * V1) / V2
Plugging in the values, we get:
M2 = (0.25M * 30.0mL) / 18.0mL
M2 = 0.4167M
So, the concentration (molarity) of the HCl solution used in the titration is 0.4167M.
I hope this helps you solve the questions! Let me know if you have any further questions.