0.070g of hydride of carbon occupies 56cm^3 at s. t.p when vaporized and contained 14.29% by mass of hydrogen. what is the formula for the hydrocarbon

C₂H₄

Step-by-step explanation:

Assume that you have 100 g of the compound.  

Then you have 85.71 g of C and 14.29 g of H.  

1. Calculate the moles of each element.

Moles of C = 85.71  × 1/12.01  =  7.130 mol C

Moles of H = 14.29 × 1/1.008  = 14.18  mol H

2. Calculate the molar ratios.  

Divide all values by the smallest number.

C:   7.130/7.130 = 1

H: 14.18/7.130   = 1.986

3. Determine the empirical formula

Round off all numbers to the closest integer.  

C:  1

H: 2

The empirical formula (EF) is CH₂.

4. Calculate the EF mass

EF Mass = (12.01 + 2.016) u

EF Mass = 14.03 u

5. Calculate the moles of compound

STP is 0 °C and 1 bar.

1 mol of a gas occupies 22.71 dm³ at STP.

56 cm³  = 0.056 dm³     Convert to moles

              = 0.056 × 1/22.71

              = 2.47 × 10⁻³ mol

6. Calculate the molar mass

MM = mass/moles

       =    0.070 g/2.47 × 10⁻³ mol

       = 28.39 g/mol

7. Calculate the molecular formula (MF)

The molecular formula is an integral multiple of the empirical formula.

MF = (EF)ₙ

  n = MF Mass/EF Mass  

     = 28.39 u/14.03 u  

     = 2.023

     ≈ 2

MF = (CH₂)₂

      = C₂H₄

The molecular formula is C₂H₄.

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).