Question:1 You dissolve 312 mg of a compound (A w B x C y D z ) in water produci

Question

Question:1
You dissolve 312 mg of a compound (AwBxCyDz) in water producing 14.31 mL of solution and use the photometer and standard solutions to find that the concentration of the A is 1.24 x 10-2 M. The molar mass of A is 114.52 g/mol.

Moles of A in the solution sample:________________________________

Mass of A in the solution sample: _________________________________

Mass % of A in the compound: _______________________________

Moles of A in 100 grams of the compound: ________________________________



Question:2
The compound, AwBxCy, like all compounds has an oxidation number of 0 (zero). The oxidation number of A is +1, the oxidation number of B is +2, and the oxidation number of C is –1. If there are two moles of A for every 3 moles of C in one mole of the compound, what is the empirical formula of the compound?



Question:3
Given the compound, KwAlx(SO4)y(H2O)z. 100.00 grams of the compound contains 8.24 grams of potassium and 5.69 grams of aluminum. What is the formula of the compound?

Explanation / Answer

There are multiple questions here . i am allowed to answer only 1 at a time. I will answer 2nd question for you since question 1 is not visible properly. Please ask other as different question.

1.
Concentration of A = 1.24*10^-2 M
V = 14.31 mL = 0.01431 L
Moles of A = concentration * volume
    = (1.24*10^-2) * 0.01431
     =1.77*10^-4 mol

mass of A = number of moles * molar mass
   = 1.77*10^-4 * 114.52
   =0.02 g

mass % of A = mass of A *100 /mass of compound
    = 0.02*100/0.312
    =6.5 %

mass % of A = mass of A *100 /mass of compound
6.5 = m*100/100
m=6.5 g

Answers:
a) 1.77*10^-4 mol
b) 0.02 g
c)6.5%
d) 6.5 g

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