1) A compound contains 59 % C, 6./2 % H and 53.4 % b) If the molecular weight of
ID: 704010 • Letter: 1
Question
1) A compound contains 59 % C, 6./2 % H and 53.4 % b) If the molecular weight of the compound is 60.0 g/mol, what is its molecular formula? by mass. a) What is its empirical formula? *2) In an experiment, 6.45 g of sulfur mixed with excess amount of Zinc. Assume that these substances react according to the equation 8Zn + Sg >8Zns, What amount of zinc sulfide was produced? How many grams of zinc was consumed? -x 3) A mixture e containing 13.5 g of oxygen, O2, and 60.4 g of nitrogen, N2, exerts a total pressure of 2.1 3 atm at 25 C. What is the volume of container, and what are the partial pressures of each gas? 4) Calculate the enthalpy change when 14.5 g of water vapor condenses to liquid water at 100 c. AH° condensation-_ 4.07 x 1 0 4(J/mol) Using these reactions, find the standard enthalpy change for the formation of I mol of Pbo (s) lead metal and oxygen gas: e 5) Pb(s) + PbO (s) + C (graghite) ?Pb (sJ + co (g) 2C ( graghite) to2 (g)->2CO (g) 2. ?H? 106.8 KJ ??'--22 1.0 KJ X 6) A student combine 1.40g of sodium bicarbonate with excess hydrochloric acid. If CO, is c 722 torr and 17 C, what volume CO2 will occupy?Explanation / Answer
Ans 2
Mass of S8 = 6.5 g
Moles of S8 = mass/molecular weight
= 6.5g / 256.48 g/mol
= 0.0253 mol
The balanced reaction
8Zn + S8 = 8ZnS
1 mol S8 produces = 8 mol ZnS
0.0253 mol S8 produces = 8 x 0.0253 = 0.2024 mol ZnS
Mass of ZnS produced = moles x molecular weight
= 0.2024 mol x 97.474 g/mol
= 19.728 g
Moles of Zn consumed
= 8 mol Zn x 0.0253 mol S8 / 1 mol S8
= 0.2024 mol
Mass of Zn consumed = moles x molecular weight
= 0.2024 mol x 65.38 g/mol
= 13.23 g
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