I'm showing the procedure of the lab and what was asked. What I have question on is towards the end. Much help would be appreciated a lot!!
First I had to balance the equation given to me:
2 Na HCO3 (s) Δ over arrow (produces)
Na2 CO3 (s) + CO2 (g) + H2O (g).
From the lab observations:
A. Mass of evaporation dish & watch glass = 75.705 g
B. Mass of evaporating dish, watch glass, & NaHCO3 = 78.605
C. Mass of evaporating dish, watch glass, & Na2CO3 = 57.460 g
1.) Using your data, calculate the mass of Na2CO3 produced?
75.705g - 57.460 g = 18.245 g
2.) Calculate the mass of NaHCO3 that decomposed?
78.605 g - 75.705 g = 2.9
If correct sig figs, wouldn't the answer be 2.9000 or just 2.9?
Wouldn't this affect my answer if correct sig figs aren't correct?
4.) Using your data, calculate how many grams of Na2CO3, Theoretically should have been produced using stoichiometry? (Hint use your calculated amount of NaHCO3 to start the stoich... chart & refer to balanced.
baking soda Δ> carbon dioxide + water + sodium carbonate
2 NaHCO3 Δ CO2 + H2O + Na2CO3
Answer (I know this isn't right! Can someone break down the process including numbers of what to multiply with what etc.) :
2.900 g NaHCO3 x 1molNaHCO3/ 84.0059 gNaHCO3 x 1molNa2CO3/ 2 mol NaHCO3 x 105.988 g Na2CO3 / 1mol Na2CO3 = 1.829 g Na2CO3
Is that correct though?
Now #5 asks calculate percent yield & use experimental mass of Na2CO3 which is 18.245... & theoretical amount of Na2CO3 which is (1.829) BUT IDK IF THAT's RIGHT (please check my math!! THANKYOU SO MUCH...based on the stoichiometry...
18.245 / 1.829 x 100 = 997.5
That does not seem right though. so, where did I go wrong?
2. It is good to five sig figures.
4, right, but obviously something else is wrong.
5. What is wrong is your mass of the final is wrong.
You can't start out with the empty apparatus mass greater the final apparatus weight with product.
I only did that ^ to get your attention. Thankyou for your help..
2. so is it 2.9000 because technically that's wrong cuz theres 3 digits on the right of the period right?
or is it 20.900 but that woudn't make sense. even if it was 02.900, the zero wouldn't matter. so what is the number may I ask?
so #4 is good?
#5 How do I fix it? Really confused at this point. Please help. Would really appreciate it.
aint no body got time to answer this!
Let's break down the process and address your questions step by step:
1) To calculate the mass of Na2CO3 produced, subtract the mass of the evaporating dish, watch glass, and Na2CO3 (57.460 g) from the mass of the evaporating dish and watch glass (75.705 g):
Mass of Na2CO3 = 75.705 g - 57.460 g = 18.245 g
Your calculation is correct.
2) To calculate the mass of NaHCO3 that decomposed, subtract the mass of the evaporating dish and watch glass (75.705 g) from the mass of the evaporating dish, watch glass, and NaHCO3 (78.605 g):
Mass of NaHCO3 = 78.605 g - 75.705 g = 2.900 g
For significant figures, you're right that the answer should be rounded to the correct number of decimal places. Since the value 2.900 g has four decimal places, the answer should also have four decimal places: 2.9000 g.
4) To calculate the theoretical mass of Na2CO3 produced using stoichiometry, follow these steps:
- Start with the mass of NaHCO3 that decomposed (2.900 g).
- Convert the mass of NaHCO3 to moles using the molar mass of NaHCO3 (84.0059 g/mol).
- Set up the stoichiometry ratio with the coefficients from the balanced equation.
- Convert the moles of NaHCO3 to moles of Na2CO3.
- Convert the moles of Na2CO3 to grams using the molar mass of Na2CO3 (105.988 g/mol).
The calculation should be as follows:
2.900 g NaHCO3 x (1 mol NaHCO3 / 84.0059 g NaHCO3) x (1 mol Na2CO3 / 2 mol NaHCO3) x (105.988 g Na2CO3 / 1 mol Na2CO3) = 1.829 g Na2CO3
Your calculation is correct.
5) To calculate the percent yield, divide the experimental mass of Na2CO3 (18.245 g) by the theoretical mass of Na2CO3 (1.829 g), and multiply by 100 to get the percentage:
Percent Yield = (18.245 g / 1.829 g) x 100 = 997.1 %
It seems like you made a calculation error in your final result. The correct answer should be 997.1%, not 997.5%.
In summary, the calculated values are as follows:
- Mass of Na2CO3 produced: 18.245 g
- Mass of NaHCO3 decomposed: 2.9000 g
- Theoretical mass of Na2CO3 produced: 1.829 g
- Percent yield: 997.1%