Question

A 0.050-mol sample of this compound weighs 940 g. The molecular formul is , and 34.1% oxygen. The molecular formula of this compound 3. A particular compound contains, by mass, 25.5% carbon, 40.4% fluo 4. Calculate the number of moles of sulfuric acid in 2.00 L of 18.5 M H2SO4, concentrated sulfuric acid. 5. Determine the molarity of 0.650 L solution containing 0.356 mol of CoCl2 6. Determine the molarity of 0.450 L solution containing 2.35 g of CoSO4. (FM155) 7. Determine the mass of solute in 1.850 L of 0.2500 M AgNO, solution. (FM169,9)

Answer 1

3)

1st calculate molar mass using:

number of mol = mass / molar mass

0.050 mol = 9.40 g / molar mass

molar mass = 188 g/mol

we have mass of each elements as:

C: 25.5 g

F: 40.4 g

O: 34.1 g

Divide by molar mass to get number of moles of each:

C: 25.5/12.01 = 2.1232

F: 40.4/19.0 = 2.1263

O: 34.1/16.0 = 2.1313

Divide by smallest to get simplest whole number ratio:

C: 2.1232/2.1232 = 1

F: 2.1263/2.1232 = 1

O: 2.1313/2.1232 = 1

  

So empirical formula is:CFO

Molar mass of CFO,

MM = 1*MM(C) + 1*MM(F) + 1*MM(O)

= 1*12.01 + 1*19.0 + 1*16.0

= 47.01 g/mol

Now we have:

Molar mass = 188.0 g/mol

Empirical formula mass = 47.01 g/mol

Multiplying factor = molar mass / empirical formula mass

= 188.0/47.01

= 4

So molecular formula is:C4F4O4

Answer: C4F4O4

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