Hello, Can you please help me with the following questions...Thanks so much!! 17

Question

Hello,

Can you please help me with the following questions...Thanks so much!!

17. Complete and balance the combustion reaction 18, What is the empirical formula of a compound that contains 27.0% S, 13.4%, and 59.6% Cl by mass? 19. What is the molecular formula of the substance with molecular weight of 356.9 g and empirical formula determined in problem 19? 20. Lithium and nitrogen react to produce lithium nitride. How many moles of N2 are needed to readt with 0.550 mol of lithium? 6 Li (s) + N2 (g) 2 Li,N (s) 21·The combustion of ammonia in the presence of excess oxygen yields NO2 and H2O. How many grams of H O is produced from the combustion of 43.9 g of ammonia? 4M,(g) +702(g) 4 NO2 (g) + 6 H2O(g)

Explanation / Answer

A combustion is a reaction with the form

CxHyOz + O2 --- H2O + CO2, CO2 and H2O are produced when a reactant is formed by C, H and O so

C4H8O2 + O2 ===== H2O + CO2 .... balance the carbon, multiply CO2 by 4

C4H8O2 + O2 ===== H2O + 4CO2, there are 8 hydrogens on the left and 2 hydrogens on the fight, multiply the h2o by 4

C4H8O2 + O2 ===== 4 H2O + 4CO2........ there are 4 oxygens on the left and 12 oxygens on the right, multiply by 5 the oxygen

C4H8O2 + 5O2 ===== 4 H2O + 4CO2

question 2

molar mass of S is 32.065

molar mass of O is 16

molar mass of Cl is 35.5

divide each percentage by the molar mass

For S

27 / 32.065 = 0.842

For O

13.4 / 16 = 0.8375

For Cl

59.6 / 35.5 = 1.6788

find the smallest value (0.8375) divide the last values by the smalles value

0.842 / 0.8375 = 1.005

0.8375 / 0.8375= 1

1.6788 / 0.8375 = 2

these numbers are the coefficients so the empirical formula is

SOCl2

Question 3

molar mass of SOCl2 is 32.065 + 16+ 35.5*2 = 119.065

divide 356.9 / 119.065 = 2.99 or 3

multiply all the coefficients by 3 so

S3O3Cl6

question 4.

6 moles of lithium needs 1 mole of N2

there are 0.55 moles of lithium so, divide this value by 6

0.55 / 6 = 0.091666 moles of nitrogen are required

question 5

4 moles of NH3 produces 6 moles of H2O

ammonia has a molar mass of 17 g/gmol

there are 43.9 grams of ammonia

moles = mass / molar mass = 43.9 / 17 = 2.582 moles

the moles of h2o produced will be

2.582 * 6 / 4 = 3.873 moles of H2O

molar mass of water is 18

mass of water is moles * molar mass

mass of waterr = 18 * 3.873 = 69.714 grams of water produced

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