Question

Walan 6 Iron metal reacts with chlorine gas according to the equation: 2Fe(s) + 3Cl2(g) 2FeCl(s) T135.0 g each of iron and chlorine react, how much FeCl, will be formed? A 102 g B 155 g 53.48 D. 80.08 E 68.0 8 7. In the process of obtaining lead from Pbs, or galena the galena is "roasted" (heated in the presence of oxygen), so that the following reaction occurs: 2PbS(s) + 30,(g) 2PO(S) + 2SOxg) IF 50.0 g of PbS reacts with 250 g of oxygen, how many grams of PbO will be formed? A 116g B 46.6 g C. 163 g D. 69.9 g E 9328 are actually obtained, the percent yield is 8. If the theoretical yield for a reaction is 54.9 g and 51.3 A. 0.934% B. 93.4% C. 107% D. 3.60% E not enough information given 9. Which of the following processes is endothermic? A. burning gasoline in an internal combustion engine B. evaporation of perspiration on your skin C. burning wood in a fireplace D. condensing steam on a mirror E, hot coffee cooling down as it sits on the table 10. How much heat energy would be needed to raise the temperature of a 15.0 g sample of iron (C-0448 J/g"C) from 22.0°C to 100.0°C? A. 34.9 B. 672J C 524 J D. 1.17 x 10' E. not enough information given

answer all please

Answer 1

6) The given reaction is,

2Fe(s) + 3C12(g) + 2FeCl3

No. of moles of Cl2 = 35 / molar mass of Cl2

= 35 / 70.8 = 0.494

No. of moles of iron = 35 / molar mass of Fe

= 35 / 55.845 = 0.626

0.626 moles of Fe will react with (3/2 X 0.626) moles of Cl2 = 0.939 moles of Cl2

Here we have only 0.494 moles of Cl2, which is less than required.

Hence Cl2 is the limiting reagent in this reaction and amount of FeCl3 will depend on amount of Cl2.

0.494 moles of Cl2 will give (2/3 X 0.494) moles of FeCl3 = 0.329 moles of FeCl3

Molar mass of FeCl3 = 162.2 g / mol

Therefore amount of FeCl3 obtained = 162.2 $\times$ 0.329 = 53.36 g $\approx$ 53.4 g

7 ) The reaction is as follows,

2PbSs) + 302(g) +2P60(s) + 2SO2(g)

No. of moles of PbS = 50 / molar mass of PbS = 50 / 239.2 = 0.209 moles of PbS

No. of moles of O2 = 25 / molar mass of O2 = 25 / 32 = 0.781 moles of O2

0.209 moles of PbS will react with (3/2 $\times$ 0.209 )moles of O2 = 0.313 moles of O2

Here we have 0.781 moles O2, thus the limiting reagent is PbS.

0.209 moles of PbS will give (2/2 $\times$ 0.209 ) moles of PbO = 0.209 moles of PbO

Molar mass of PbO = 223.2 g / mol

Amount of PbO obtained = 223.2 $\times$ 0.209 = 46.6 g

8) Percent yield = (actual yield / theoretical yield ) $\times$ 100 %

   Actual yield = 51.3 g

   Theoretical yield = 54.9 g

Percent yield = ( 51.3 / 54.9 ) $\times$ 100 %

= 93.4 %

9) Here evaporation on the perspiration on the skin is an endothermic process. This process requires heat.Here substance goes from a liquid phase to a gaseous phase, this is because molecules get excited by absorbing the energy ( heat energy ) from the surroundings.

Other processes given here liberates heat or energy and thus they are exothermic reactions.

10) Heat , Q = mC$\Delta$T

m = 15 g

C = 0.448 J/g0C

$\Delta$T = 100 0C - 22 0C = 78 0C

Q = 15 $\times$ 0.448 $\times$ 78

   = 524.16 J