Directions: Fill the water bottles with vinegar and weigh them, fill the balloon

Question

Directions:

Fill the water bottles with vinegar and weigh them, fill the balloons with 5 g of baking soda (each balloon gets the same amount this time) and place the balloons on the water bottles. Add the baking soda to the vinegar and shake gently to get complete mixing. The baking soda should be the limiting reactant so make sure it all dissolves. Don't wait too long (or the carbon dioxide may leak out of the balloon) and use the string/yarn to measure the circumference of the filled balloon. Repeat the experiment three times.

Data:

Answer the following questions:

1) Why did we need to convert temperatures to Kelvin?

2) What would you change if you had used 15 g of baking soda for this experiment and kept every other detail the same?

3.) Check the weather report for the day you performed the experiment. What was the barometric pressure that day? (You do not need the value at the exact time you do the experiment.) How does your calculated pressure compare to that pressure? Should they be similar? Barometric pressure was 29.62 Hg

4.) Think about the approximations made in this experiment. List three and explain whether you believe they are reasonable or not and explain your reasoning.

Ideal Gas Law Data Trial # Mass of CH3COOH (g) Mass of NaHCO3 (g) Circumference of Balloon 1 105.4g 5g 16.5 in 2 119.5g 5g 16 in 3 109.3g 5g 16 in

Explanation / Answer

1. When calculating the volume by gas law PV= nRT will be used.

Here R is talen in LIt.atm/mole.K

since the temperature is expressed in K, while calculting the no of moles or any parameter related to gas equation, temperature has to be taken in K.

2. the reaction between acetic acid and NaHCO3 is

CH3COOH+ NaHCO3--------->CH3COONa + H2O+CO2

1 mole of acetic acid reacts with 1 mole of NaHCO3. molar ratio of CH3COOH: NaHCO3= 1:1

moles = mass/ molar mass

molar mass : NaHCO3= 84 and CH3COOH= 60

moles   in 105.4 gm of acetic acid = 105.4/60 =1.76, second trail = 119.5/60 =1.99 third trial = 109.3/60=1.82

when 15 gm of NaHCO3 is taken, moles =15/84= 0.18

since NaHCO3 is limiting reactant and controls the moles of CO2 formed. moles of CO2 formed changes.

3. The calculate pressrue = nRT/V= 0.06*0.0821*340.15/1.24= 1.35 atm. This is greater than the atompsheric pressure since the gas generated exerts additional pressure.

4. the reaction is between weak acid and weak base is slow. To ensure completion of reaction, 1 reactant is taken as excees.

carbonic acid is formed whicj decomosed completely.

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