# Chem Urgent

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Volume of stock solution
a. 5.0mL b.10.0mL c.15.0mL d.20.0mL
Prepare 25mL of each of the four different dilute solution
Concentration of stock- 1.01E-5
Calculate molarity for a,b,c,d

Molarity=m1V1/V2
for a would the answer be 2.02E6?????
(1.01E-5)(5.0)/(25.0)

• Chem Urgent -

Yes, the answer is what you posted EXCEPT the exponenet is -6 and not +6. Also, you don't say if th e stock solution is molar, molal, or what. Your answer is ok if the stock solution is 1.01E-5 MOLAR

• Chem Urgent -

Its Molar. Thanks

• Chem Urgent -

If for a. the concentration is 2.02E-6, Wavelength at 630, Absorbance is .216, how would I find the %T.

• Chem Urgent -

Absorbance = 1/T OR 100/%T.

• Chem Urgent -

What do you mean? I know the equation is %T=It/Io*100
A=log(Io/It)=-logT

I don't know how to use it and plug in the information I have.

• Chem Urgent -

A = log (1/T)
0.216 = log (1/T)
1.644 = 1/T
T = 0.608
%T = 60.8%

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