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1.Calculate the formula weight of each of the following to three significant figures, using a table of atomic weight (AW): (a) chloroform CHCl3 (b) Iron sulfate Fe2 (SO4)3.
2. Calculate the molecular mass (formula mass) of C6H12O6?
3.Calculate the molecular mass of C12H22O11?
Can anyone give me questions like this

deapan , 9 Years ago
Grade 9
anser 4 Answers
A M S ARUN KRISHNA

Last Activity: 9 Years ago

Solution
  1.  a.chloroform
1 x AW of C = 12.0 amu
1 x AW of H = 1.0 amu
3 x AW of Cl = 3 x 35.45 = 106.4 amu
Formula weight of CHCl3 = 119.4 amu
The answer rounded to three significant figures is 119 amu.
  1. b. Iron(III)Sulfate
2 x Atomic weight of Fe = 2 x 55.8 = 111.6 amu
3 x Atomic weight of S = 3 x 32.1 = 96.3 amu
3 x 4 Atomic weight of O =12x16 = 192.0 amu
Formula weight of Fe2 (SO4)3 = 399.9 amu
The answer rounded to three significant figures is 4.00 x 102 amu.
 
  1. 6 ×    AW of C =         72
12  × AW of H =         12
6  ×   AW of O =         96
     = 72 amu + 12amu + 96 amu =  180 amu = molecular mass of C6H12O6
  1. 12  ×   AW of C   =  144
22  ×   AW of H   =   22
11  ×   AW of O  =   176
     =  144 amu + 22 amu + 176 amu   =  342 amu = molecular mass of C12H22O11
 
Problems for Practice
Calculate the formula masses of the following compounds
a. NO2                            b. glucose (C6H12O6)                                     c. NaOH                               d. Mg(OH)2
e. methanol (CH3 OH)                                                                   f. PCl3                                                    g. K2 CO3

Neeti

Last Activity: 9 Years ago

You'll get such questions in the chapter Mole concept from any good book

deapan

Last Activity: 9 Years ago

Neeti I want questions immediately to prepare for my exam

Neeti

Last Activity: 9 Years ago

Well i can`t copy and paste questions here i`ll have to type them all, and it`s better if you get a book it`ll be easier for you to solve it that way. :)

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