Urgent... Someone please help!!
Can someone please check to see if I am doing these correctly, I have a test tomorrow... Thank you :)
Q) Calculate the new molarity of a 35mL sample of 0.450 M CaCl2 solution that is diluted with enough water to make 250 mL of solution.
A) 0.450 m CaCl2 x 35mL/250mL = 0.063 mL diluted solution
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Q) Calculate the new molarity of a 35mL sample of 0.450 M CaCl2 solution that is diluted with enough water to make 250 mL of solution.
A) M1V1 = M2V2
M1 = 0.450
M2 = ?
V1 = 0.035 L
V2 = 0.250 L
M2 = M1 X V1/V2
0.450 X (0.035L/0.250L) = 0.063
Given: 450 mL (0.450L); 0.250 M KNO
Need: Mass of KNO
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Q) What mass of KNO3 (MW=101) is needed to prepare 450mL of 0.250 M KNO3 in water?
A) 0.450 L Solution x 0.250 M KNO/1 L solution x 101g KNO/1 mol KNO
= 11.4 g KNO
For the first question:
To calculate the new molarity of a solution, you can use the equation M1V1 = M2V2, where 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 0.450 M, the initial volume (V1) is 35 mL, and the final volume (V2) is 250 mL.
Using the equation, you can solve for M2:
M2 = M1 * V1 / V2
Plugging in the values:
M2 = 0.450 M * 35 mL / 250 mL
M2 = 0.063 M
So the new molarity of the solution after dilution is 0.063 M.
Now, let's move on to the second question:
To find the mass of a compound needed to prepare a certain molarity of a solution, you can use the equation:
Mass = Volume (in liters) * Molarity * Molar mass
In this case, the volume is given as 0.450 L, the molarity is 0.250 M, and the molar mass of KNO3 is 101 g/mol.
Plugging in the values:
Mass = 0.450 L * 0.250 M * 101 g/mol
Mass = 11.4 g
So you would need 11.4 g of KNO3 to prepare 450 mL of a 0.250 M KNO3 solution.