Complete combustion of a 17.12mg sample of xylene In oxygen yielded 56.77mg
1 answer:
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Answer:
1) 2.0 g
2) 0 g
3) 4.17 g
4) 2.57 g
Explanation:
First of all, we need to know the compounds and the reaction. The ion carbonate is , and the ion nitrate is
.
Sodium is in group 1, so it must lose one electron to be stable, and be the cation . Silver has only one electron too, so the cation will be
.
To form the chemical compounds, first we put the cation, then the anion, and change their charges without the signal:
Sodium carbonate: Na2CO3
Silver nitrate: AgNO3
Silver carbonate: Ag2CO3
Sodium nitrate: NaNO3
The balanced reaction will be:
Na2CO3 + 2 AgNO3 --> Ag2CO3 + 2 NaNO3
Now, we must check the stoichiometry, which will be 1:2:1:2 (always in number of moles)
The question wants to know the mass value, so we need to know the molar mass of these compounds. Checking the periodic table will see that:
Na = 23 g/mol, C = 12 g/mol, N = 14 g/mol, O = 16 g/mol, Ag = 108 g/mol
So the molar mass of the compounds must be:
Na2CO3 = 106 g/mol (2x23 + 12 + 3x16)
AgNO3 = 170 g/mol (108 + 14 + 3x16)
Ag2CO3 = 276 g/mol (2x108 + 12 + 3x16)
NaNO3 = 85 g/mol
We have a mixture of the reactants, so one probably would be in excess, so, first will need to test. Let's do the stoichiometry calculus using silver nitrate as the limit, so:
1 mol of Na2CO3 ---------- 2 mol of AgNO3
106 g ------------------------------ 2x170 = 340 g
x ------------------------------------ 5.14 g
By a simple direct three rule:
340x = 544.84
x = 1.6 g of Na2CO3
That means that for this reaction, we only need 1.6 g of Na2CO3 to react with 5.14 of AgNO3. How we have 3.60 g of Na2CO3, it is on excess, and all the AgNO3 will be consumed.
1) The mass of Na2CO3 that remains after the reaction will be the initial less the mass that reacted:
m = 3.6 - 1. 6 = 2.0 g
2) All the AgNO3 reacted, so there isn't a mass present after the reaction.
m = 0 g
3) Now, doing the stoichiometry calculus between AgNO3 and Ag2CO3
2 moles of AgNO3 ------------- 1 mol of Ag2CO3
2x170 g ------------------------------- 276 g
5.14 g --------------------------------- x
By a simple direct three rule:
340x = 1418.64
x = 4.17 g of Ag2CO3
4) Now, doing the stoichiometry calculus between AgNO3 and NaNO3
2 moles of AgNO3 ----------------------- 2 moles of NaNO3
2x170 g ---------------------------------------- 2x85 g
5.14 g ------------------------------------------- x
By a simple direct three rule:
340x = 873.8
x = 2.57 g
Answer:
Title for the lab--->Calorimetry and Specific Heat
Name:
Teacher:
Date:
Purpose: Explore how the specific heat of a substance can be determined using a “coffee cup” calorimeter.
Question: How can you determine the specific heat of a metal using a calorimeter?
Hypothesis: If a metal has a low specific heat, then the metal could make an excellent material for cookware because it takes less heat to raise the temperature of the metal to cook food.
MATERIALS:
- Two polystyrene coffee cups
- Lid for polystyrene cup
- Thermometer
- 250 mL beaker
- 400 mL beaker
- Ring stand
- Two buret clamps
- Hot plate
- Test-tube holder
- 50 mL graduated cylinder
- Water
- aluminum, copper, iron, and lead powder
- Analytical balance
PROCEDURE:
1) Set up a 600 mL beaker and add 400 mL of dis"lled water inside and place it on a hot plate un"l it boils. Also set up 2 dry Styrofoam cups with a lid aside and add 100.0 mL tap water (calorimeter water) inside.
2) In the boiling water, place the unknown metal sample inside for about 30 min. Before though, weigh it accurately and record the mass on your data sheet.
3) After 30 min, take the temperature of boiling water to the nearest 0.1 °C (Ini"al temp of metal), then take the metal out of the boiling water and replace it into Styrofoam cups filled with room temperature tap water. Ini"al temperature of water is the room temperature of the tap water.
4) Take every 15 seconds for about 2 minutes the temperature of water inside the calorimeter with a thermometer inserted through the hole in the lid. Gently swirl the cup to mix the contents and record the temperature. Use the highest temperature.
5) Calculate the specific heat of the metal sample.
then the table will be in the picture i posted on here
next is your ---> Analysis /Conclusion
Analysis:
Analyzed from the data above, we know the temperature that is measured depends on the amount of mole in the solution. If the amount of mole in the solution is large, the temperature will be as well. After a few moments, the temperature rises and falls, and in some instances, it remains steady.
Conclusion:
In conclusion, I do believe my hypothesis was supported through my experiments. Through said experiments, I identified the unknown metal as we calculated the changes in the heat, and found that the metals that should be put to use are copper and iron metals. Copper and iron have a low specific heat, which makes these ideal metals when creating cookware. When a metal has low specific heat, it needs less energy to produce heat and it cools down with less energy as well. For these reasons, my hypothesis is supported.
Explanation:
hope this helps :)
