Answer the following: -Calculate the mass (g) of NaHCO 3 reacted in each sample

Question

Answer the following:

-Calculate the mass (g) of NaHCO3 reacted in each sample

-What is the mass (g) of NaHCO3 in each tablet?

-Calculate the mass (g) of CO2(g) in each capsule

-How many moles of CO2(g) were collected in each sample?

-Calculate the volume (L) CO2(g) generated in each sample

Trial 1 Trial 2 Mass: gelatin capsule (g) 0.119 0.123 0.121 Mass: whole alka-seltzer tablet (g) 3.254 3.254 3.254 Mass: capsule + alka-seltzer sample (g) 0.926 0.860 0.845 Mass: system before reaction (g) 36.038 37.541 37.733 Mass system after reaction (g) 34.886 36.189 34.706 Temperature (°C) 21.5 22.0 22.1 Pressure (mmHg) 777.0 777.0 777.0 Volume of water collected (mL) 123.7 118.1 120.9

Answer the following:

-Calculate the mass (g) of NaHCO3 reacted in each sample

-What is the mass (g) of NaHCO3 in each tablet?

-Calculate the mass (g) of CO2(g) in each capsule

-How many moles of CO2(g) were collected in each sample?

-Calculate the volume (L) CO2(g) generated in each sample

INTRODUCTION Alka-Seltzer tablets consist of sodium bicarbonate (NaHCO3), citric triprotic), acetyl salicylic acid (as NaHCO3 components react as follows citric acid is pirin) and other ingredients. When dissolved in water, citric acid and acid (H,CsHsO7i 3NaHCO3(aq) + H3C6Hso,(aq) Na,C6H3O7(aq) + 3H20() +3 CO2(g) (1) To determine the mass of NaHCOs in a tablet, we will use a known mass of a powdered sample and determine the mass of generated CO2. For this analysis to work, NaHCOs must be the limiting reagent. Since this is not true for the components in the tablet, we will add HCl(aq). HCl(aq) is a strong acid while citric acid is a weak acid. With the two acids in the same solution, the NaHCO3 will first react with HCl and NaHCO3 will react with citric acid only if the HCl has been completely consumed. The amount of HCl we will use in this lab is such that citric acid will not react. The reaction between NaHCO3 and HCl is NaHCO3(aq) + HCl(aq)NaCl(aq) + H2O(/) + CO2(g)

Explanation / Answer

               

                                         

NaHCO3 (s) + HCl(aq) -----> NaCl(aq)+H2O(l)+CO2(g)

Trial 1

Calculate the mass (g) of CO2 (g) in each capsule

Mass: system before reaction (g) 36.038             

Mass system after reaction (g)   34.886

Loss in mass = 36.038 - 34.886 = 1.152 g

Loss in mass = Mass of CO2 evolved = 1.152 g

Moles of CO2 (g) were collected in each sample

Molar mass CO2 = 44.01 g/mol

Moles of CO2 = 1.152 g/44.01 = 0.0262

Calculate the mass (g) of NaHCO3 reacted in each sample

Moles of NaHCO3 consumed = Moles of CO2 evolved = 0.0262

Molar mass of NaHCO3 = 84.007 g/mol

Mass of NaHCO3 = 0.0262 mol x 84.007 g/mol = 2.20 g

The mass (g) of NaHCO3 in each tablet

Mass: whole alka-seltzer tablet 3.254 g

The mass (g) of NaHCO3 in each tablet = (2.20 g /3.254 g) x 100 = 67.61%

Calculate the volume (L) CO2 (g) generated in each sample

Total pressure = vapor pressure of water + CO2 gas pressure

CO2 gas pressure = Total pressure - vapor pressure of water

777.0 (mmHg) - 18.777 (mmHg) = 758.223 mmHg

Temperature 21.5(°C) = 294.5 K

R = 62.363 L mmHg K1 mol1

Calculate the volume (L) CO2 by using ideal gas equation

PV = n RT

V = n RT/P

V = (0.0262moles x 62.363 L mmHg K1 mol1 x 294.5 K)/758.223mmHg

V = 0.634L

Trial 2

Calculate the mass (g) of CO2 (g) in each capsule

Mass: system before reaction (g) 37.551

Mass system after reaction (g)   36.189

Loss in mass = 37.551 - 36.189 = 1.362 g

Loss in mass = Mass of CO2 evolved = 1.362 g

Moles of CO2 (g) were collected in each sample

Moles of CO2 = 1.362 g/44.01 = 0.0309

Calculate the mass (g) of NaHCO3 reacted in each sample

Moles of NaHCO3 consumed = Moles of CO2 evolved = 0.0309

Mass of NaHCO3 = 0.0309 mol x 84.007 g/mol = 2.60 g

The mass (g) of NaHCO3 in each tablet

Mass: whole alka-seltzer tablet 3.254 g

The mass (g) of NaHCO3 in each tablet = (2.60 g /3.254 g) x 100 = 79.90%

Calculate the volume (L) CO2 (g) generated in each sample

Total pressure = vapor pressure of water + CO2 gas pressure

CO2 gas pressure = Total pressure - vapor pressure of water

777.0 (mmHg) – 19.8 (mmHg) = 757.2 mmHg

Temperature 22(°C) = 295 K

Calculate the volume (L) CO2 by using ideal gas equation

PV = n RT

V = n RT/P

V = (0.0309 moles x 62.363 L mmHg K1 mol1 x 295 K)/757.2 mmHg

V = 0.750L

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