Q80P

Question

Calcium nitrate and ammonium fluoride react to form calcium fluoride, dinitrogen monoxide, and water vapor. What mass of each substance is present after 16.8 g of calcium nitrate and 17.50 g of ammonium fluoride react completely?

Step-by-Step Solution

Verified
Answer

         (a) The mass of NH4F left is 9.91 g.

         (b) The mass of Ca(NO3)2 left is 0 g.

         (c) The mass of CaF2 is 7.99 g.

         (d) The mass of N2O is 9.01 g.

         (e) The mass of H2O is 7.38 g.

1Step 1: Balance the chemical equation

In a balanced chemical equation, the number of atoms on the reactant side should be the same as the number of atoms on the product side for a particular atom. For balancing the reaction, the atoms are multiplied by the stoichiometric coefficient.

So, the balanced chemical equation is:

Ca(NO3)2(s)+2NH4F(aq) CaF2(s)+2N2O(g)+4H2O(I)

2Step 2: Relation between mass and number of moles

The number of moles is calculated by the mass and Molar mass. The relationship between the number of moles, mass, and molar mass is given below.

Number of moles=massMolar mass

3Step 3: Calculate the number of moles of Ca ( NO 3 ) 2

The mass ofCa(NO3)2= 16.8 g.

The molar mass ofCa(NO3)2= 164.1 g/mol

Thus, the number of moles ofCa(NO3)2is:Number of moles of Ca(NO3)2=mass of Ca(NO3)2Molar mass of Ca(NO3)2                                                        =            16.8 g164.1 g/mol                                                        =              0.1024 mol

4Step 4: Calculate the number of moles of NH 4 F

The mass of NH4F = 17.5 g.

The molar mass of  NH4F = 37.037 g/mol

Thus, the number of moles of NH4F is:

Number of moles of NH4F=mass of NH4FMolar mass of NH4F                                                        =            17.5 g37.037 g/mol                                                        =              0.4725 mol

5Step 5: Relation between the number of moles of Ca ( NO 3 ) 2 and NH 4 F

In the given reaction, 1 mol of Ca(NO3)2reacts with 2 mol of NH4F

Thus,

1 mol of Ca(NO3)2=2 mol of NH4F

6Step 6: Determine the Limiting reagent of the reaction

In the reaction, 1 mol of Ca(NO3)2reacts with 2 mol of NH4FThus,

     1 mol of Ca(NO3)2        =           2 mol of NH4F0.1024 mol of Ca(NO3)2   =    0.1024×2 mol of NH4F                                                         0.2048 mol of NH4F

Therefore, NH4F present in access in the reaction, hence Ca(NO3)2 is a limiting reagent.

7Step 7: Calculate the mass of NH 4 F left

The molar mass of NH4F = 78.07 g/mol

The number of moles NH4F left = 0.4725 mol – 0.02048 mol = 0.2677 mol

Thus, the mass of NH4F left is:

mass of NH4F left         =     moles of NH4F left×molar mass of NH4F                                     =                 0.2677 mol×37.37 g/mol                                     =                               9.91 g 

8Step 8: Calculate the mass of Ca ( NO 3 ) 2 left

Since Ca(NO3)2 is completely utilized in the reactions, thus zero moles of Ca(NO3)2 is left in the reaction. Hence, the mass of Ca(NO3)2 is zero.

9Step 9: Calculate the number of moles of CaF 2

In the given reaction, 1 mol of Ca(NO3)2 forms 1 mol of CaF2

Thus, the number of moles of CaF2 is

         1mol of Ca(NO3)2      =     1mol of CaF20.1024mol of Ca(NO3)2     =   0.1024mol of CaF2

10Step 10: Calculate the mass of CaF 2

The molar mass of CaF2 = 78.07 g/mol

Thus, the number of moles of CaF2 is:

mass of CaF2       =    moles of CaF2×molar mass of CaF2                             =     0.1024 moles×78.07g/mol                             =                         7.99 g

11Step 11: Calculate the number of moles of N 2 O

In the given reaction, 1 mol of Ca(NO3)2 forms 2 mol of N2O

Thus, the number of moles of N2Ois

       1 mol of Ca(NO3)2    =         2mol of N2O0.1024mol of Ca(NO3)2  =   2×0.1024 mol of N2O                                       =        0.2048 mol of N2O

12Step 12: Calculate the mass of N 2 O

The molar mass of N2O = 44.013 g/mol

Thus, the number of moles of N2O is:

mass of N2O        =     moles of N2O×molar mass of N2O                            =            0.2048 mol×44.013 g/mol                            =                            9.01 g

13Step 13: Calculate the number of moles of H 2 O

In the given reaction, 1 mol of Ca(NO3)2forms 2 mol of H2O

Thus, the number of moles of H2O is

       1 mol of Ca(NO3)2    =         4mol of H2O0.1024mol of Ca(NO3)2  =   4×0.1024 mol of H2O                                       =        0.4096 mol of H2O

14Step 14: Calculate the mass of H 2 O

The molar mass of  H2O = 18.02 g/mol

Thus, the number of moles of H2O is:

mass of H2O        =     moles of H2O×molar mass of H2O                            =            0.4096 mol×18.02 g/mol                            =                            7.38 g