please try to explain as simply as possible ok? And if can,step
by step! lol :D
1) A 6g of sample of pure pure carbon is completely burned in
oxygen.
C + O2 > CO2
Which mass of carbon dioxide is produced?
A) 12g B)22g
C)38g D)44g
No. of moles of C = 6/12 = 0.5
mole
according to the equation, 1 mole of C will produce
1 mole of CO2
Hence 0.5 mol C produce 0.5 mol
CO2.
Mass of CO2 = 0.5 x Mr = 0.5 x (12 + 32) =
22
ans is B
2)Which volume of sulphur dioxide ( at r.t.p) is formed when
9.7g of zinc sulphide is heated in air?
2ZnS + 3O2 > 2ZnO + 2SO2
A)1.2dm^3 B)2.4dm^3
C)3.6dm^3 D)4.8dm^3
No. of moles of ZnS = 9.7 / Mr of ZnS =
9.7/46 = 0.1 mol
According to the equation, 2 mol ZnS produces 2 mol
SO2.
Hence 0.1 mol ZnS produces 0.1 mol
SO2.
Vol. of SO2 = 0.1 x 24dm3 =
2.4dm3 ans is
B
3) Propane burns completely in oxygen as shown in the
equation.
C3H8 (g) + 5O2 (g) > 3CO2 (g) + 4H2O (l)
If 0.1 mol of propane is burnt completey,which volume of gaseous
product is obtained,measured at room temperature and pressure?
A)0.1dm^3 B)0.3dm^3
C)2.4dm^3
D)7.2dm^3
0.1 mol propane produces 0.3 mol
CO2.
Volume of gas = 0.3 x 24 dm3 =
7.2dm3 Ans is
D
4) What is the maximum mass of chromium, Cr, that can be
extracted from 76g of chromium (III) oxide, Cr2O3?
A) 48g B)52g
C)104g
D)152g
No. of moles of Cr2O3 = 76/ Mr of Cr2O3 =
76/152 = 0.5 moles
1 Cr2O3 ===> 2 Cr + 3/2
O2
or 2 Cr2O3 ===>
4 Cr + 3 O2
1 mol of Cr2O3 will produce 2 moles
Cr.
Hence 0.5 mol Cr2O3 will produce 1 mol Cr. Hence
mass of Cr = 1 x 52 = 52g
Ar of Cr = 52, Mr of Cr2O3 = 152
pleaseeeeeeeee help! Thanks in advance :D
