hello can someone please solve these 3 and create another example of each for me

Question

hello can someone please solve these 3 and create another example of each for me I would really appreciate it I have an exam in two days

ven belovw In the last section, there are 5 calculations, similar to those gi 15. Limestone (CaCos) is decomposed by heating to quicklime (CaO) and carbon dioxide. Calculate how many grams of quicklime can be produced from 1.0 kg of limestone Relative atomic masses: Ca = 40 C = 12 O=16. 16. Calculate the pH of a HNOs solution of concentration 0.02 mol dm3. 17. Ammonia is bought as "880 ammonia" (a solution of density 0.880 g cm*), whose content is 28% ammonia (ie, it contains 280 g ammonia per kilogram of solution).

Explanation / Answer

Ans. #15. Balanced Reaction:          CaCO3(s) ----heat-----> CaO(s) + CO2(g)

# Given, mass of CaCO3 taken = 1.0 kg = 1000.0 g

Molar mass of CaCO3 = (40 + 12 + 3 x 16) g/ mol = 100.0 g/ mol

Moles of CaCO3 taken = Mass/ Molar mass

                                    = 1000.0 g/ (100.0 g/ mol)

                                    = 10.0 mol

According to the stoichiometry of balanced reaction, 1 mol CaCO3 produces 1 mol CaO.

So,

            Moles of CaO produced = (1 mol CaO per mol CaCO3) x Moles of CaCO3 taken

                                                = (1 mol CaO / mol CaCO3) x 10.0 mol CaCO3

                                                = 10.0 mol CaO

Now,

            Mass of CaO produced = Moles of CaO produced x Molar mass

                                                = 10.0 mol x (56.0 g/ mol)

                                                = 560.0 g

#15. Step 1: Convert [HNO3] in terms of molarity

Given, [HNO3] = 0.02 mol dm-3                              ; [1 dm3 = 1.0 L]

                        = 0.02 mol / L                                   ; [1 mol/ L = 1 M]

                        = 0.02 M

Step 2: Balanced reaction:              HNO3(aq) + H2O -------> H3O+(aq) + NO3-(aq)

According to the stoichiometry of balanced reaction, 1 mol HNO3 yields 1 mol H+.

So, in the given solution-    [H+] = [H3O+] = [HNO3] = 0.02 M

Now,

            pH = -log [H3O+]                  ; or, pH = - log [H+]

Where, [H3O+] or [H+] must be in terms of molarity.

            Or, pH = -log 0.02

            Hence, pH = 1.70

#17. The last part of question 17 is missing. It’s assumed that we have to calculate molarity.

Given solution: Ammonia is bought as 880 ammonia (i.e. density of solution = 0.880 g/ mL).

                        Ammonia content in solution = 28%

# Step 1: For simplicity, let the volume of ammonia solution be 1.000 L = 1000.0 mL

Now,

            Mass of ammonia solution = Volume x density

                                                = 1000.0 mL x (0.880 g/ mL)

                                                = 880 g

                                                = 0.880 kg

# Step 2: Pure ammonia content in solution = 28% (w/w) of ammonia solution

                                                = (280 g NH3 / 1.0 kg solution) x 0.880 kg solution

                                                = 246.4 g NH3

# Step 3: Moles of NH3 in solution = 246.4 g / (17.0 g/ mol) = 14.494 mol

Now,

            Molarity of NH3 solution = Moles of NH3 / Volume of solution in liters

                                                            = 14.494 mol / 1.000 L

                                                            = 14.494 M

## Practice questions:

#15A. Upon thermal decomposition, a 65.0 g crude sample of CaCO3 produces 11.2 L CO2 at STP. Calculate % purity of CaCO3 in sample.

#16A. Calculate pH of 3.0% (w/v) solution of HNO3.

#17A. Ammonia is bought as “880 ammonia” (a solution of density 0.880 kg/ L). The purity of ammonia in solution is 36% (w/w). Calculate molarity of solution.

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