Often it is not the ability to solve an equation that prevents us from being abl

Question

Often it is not the ability to solve an equation that prevents us from being able to solve a problem, but it is the ability to first translate a problem into an equation. Specifically, determining what information is of importance to be able to solve the problem and which information is not needed can be tricky. I he chemistry department provided us with some problems to help improve our problem solving skills One mole of any substance is the amount of substance equal to its atomic (molecular) mass expressed in grams, Example. A carbon atom (C) has the atomic mass of 12; therefore 12 grams of carbon is one mole of carbon.

Explanation / Answer

Solution :-

Q1) given 150 g mixture

Percent Fe = 35.0 %

Mass of Fe = ?

Using the given percent of the iron lets calculate the mass of iron in the mixture

150.0 g mixture * 35.0 % iron / 100 % = 52.5 g iron

So the mass of iron in the mixture is 52.5 g

Q2) given

Mass of iron = 30.0 g

Percent of the iron = 40.0 %

Mass of mixture = ?

Mass of mixture = 30 g * 100 % / 40.0 % = 75.0 g

So the mass of mixture = 75.0 g

Q3) given

Mixture mass = 250.0 g

Mass of iron = 20.0 g

% iron = ?

% iron = (mass of iron / mass of mixture)*100%

              = (20 g / 250 g) / 100%

              = 8.0 %

So the percent of the iron is 8.0 %

Q4)

Mass of C = 12 and mass of S = 32

Therefore mass of CS2 = 12 + (2*32) = 76 g / mol

% C and % S = ?

% C = (mass of C / mass of CS2)*100%

        = (12 g / 76 g)*100%

       = 15.8 % C

Now

% S = 100 % - % C

       = 100 % - 15.8 %

       = 84.2 %

Q5 ) 156 g CH4

How many moles of CH4

Molar mass of CH4 = (4*1)+12 = 16 g per mol

Moles = mass / molar mass

Moles of CH4 = 156 g / 16.0 g per mol

                         = 9.75 mol CH4

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