Which compound has the highest nitrogen content by mass? a. KNO3 b. NO2 c. NH4CI

Question

Which compound has the highest nitrogen content by mass? a. KNO3 b. NO2 c. NH4CI d. Li3N 9. Find the percentage of the total mass that is due to water for each of the following hydrates. a. ZnSO4-7 H20 b. Mn(NO3)2 4 H20 10. Find the empirical formulas of compounds with the following percent compositions. a. 38.35% Cl and 61.65% F b. 59.35% Sr, 8.135% C, and 32.51% 11. Find the molecular formula of each compound, given its empirical formula and molar mass. a. CH20, 120 g/mol b. C2HCl, 181.5 g/mol

Explanation / Answer

Basis : 1 mole of substance,

1.moles =mass/molar mass and 1 mole means, mass= molar mass

atomic weights : K= 39, N= 14 and O= 16, Li= 7, Cl=35.5

1. mass of 1 mole of KNO3= 39+14+3*16= 101, mass % of N= 100*(mass of Nitrogen/total mass)=100* 14/101= 13.86%

2. NO2, mass of 1 mole of NO2= 14+32= 46, mass % of N =100* 14/46=30.43%

3. mass of 1 mole of NH4Cl= 14+4+35.5= 53.5, mass % of N= 100*14/53.5=26.17%

4. mass of 1 mole of Li3N= 7*3+14= 35, mass % of N= 100*14/35=40%

hihest mass % of N is there in Li3N.

2. mole =mass/molar mass and for 1 mole, mass =molar mass

Atomic weights : Zn=65.4, S= 32, H= 1 and O=16, Mn= 55 , N= 14

molar mass of ZnSO4= 65.4+32+4*16=161.4, 7H2O= 7*18= 126

molar mass of ZnSO4. 7H2O= 161.4+126= 287.4 g/mole, mass % of H2O= 100*126/287.4=43.84%

b) molar mas of Mn(NO3)2.4H2O= 55+2*(14+3*16)+4*18=251 , mass % H2O= 100*72/251=28.7%

3. Basis :100 gm of compound. It contains 38.35 gm of Cl and 61.52 g mof F

moles =mass / atomic weights, atomic weights : Cl= 35.5 and F= 20

moles of Cl : F= 38.35/35.5 : 61.65/20 =1 :3

empiricial formul is ClF3.

b) atomic weights : Sr= 88, C=12 and O= 16, basis :100 gm of substance

moles =mass/atomic weight

mass ratio of Sr: C: O= 59.35: 8.135: 32.51

mole ratio   59.35/88 : 8.135/12 : 32.51/16= 0.674: 0.67: 2 or 2/3 : 2/3 :2 or 2: 2: 6

the empirical formula is Sr2C2O6.

4. molar mas of CH2O= 12+2+16= 30, n= no of empirical formulae

n* 30 = molar mass of molecular compound, n*30=120, n= 4 hence molecular formula is C4H8O4.

molar mass of C2HCl= 2*12+1+35.5= 60.5, n*60.5 =181.5, n= 3

hence molecular formula is (C2HCl)3= C6H3Cl3.

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.