c) How many moles are present in 250 mL of a 2 M solution? Show your work. How m

Question

c) How many moles are present in 250 mL of a 2 M solution? Show your work. How much of NaCI would you measure out to make a 250 ml of 2M solution of NaCI? Show your work d) 7. Examine the Trizma base container. It reads 121.14 a) What is the molecular weight? Indicate the units. b) How much would you need to make 50 ml of an aqueous 70 mM solution of Trizma base? Sh your work. c) You have to make 50 ml ofa 70 mM solution of Trizma base in a 50 mL conical tube. Show work. d) How much diluent did you add? Show your work. e) What is the diluent?

Explanation / Answer

C) Firstly see how many moles are present in 1 liter of solution. It is given that the solution is 2M, which means there are 2 moles in 1 liter or in 1000 ml (1L=1000ml)

Now find out how many moles can there be in 250 ml. Take xM as the number of moles in 250 ml:
2M=1000ml
1M=1000/2=500ml
xM=250/500=0.5
0.5M or 0.5 Moles are present in 250 ml of 2M solution.

or

250 ml * 1liter/1000ml * 2 moles/1Liter = 0.5 moles

d) Firstly, you need to know how much moles are in 250 ml of 2 M solution, which we did in the previous question.

Next you calculate the molar mass of the NaCl which is:

Na- 22.9
Cl- 35.4
Molar mass of NaCl- 58.3 g/mol

Now you know how much NaCl is there in one mol, so calculate how much NaCl would be in 0.5 mol as we found out in the previous question:

58.3 g/mol * 0.5 mol = 291.5 grams

Question 7: (Although the data is insufficient for the question to answer because it is derived from a lab experiment, but I can still answer a few things for you)

a. If the container read 121.14 then the molecular weight is 121.14. The molecular weight of Tris base is 121.14

b. Following the similar method as we did in the 'C' question above,

7mM in 1 liter= 0.007 M in 1 Liter

50*1/1000*0.007/1 = 0,0035 moles

Now it is not specified if you need to find out the number of moles or weight of Tris base, if it is in grams, then multiply it with the molecular weight

0.00035*121.14 = 0.42 grams

e) A diluent is any substance that is added to a concentrated solution to bring down the concentration or viscosity or intensity of the given solution. Substances like water are used as a universal diluent.

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