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I did some research and found the questions:
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What is the mass of 1 mole of pennies?
How many moles of pennies have a mass equal to the mass of the moon?
Solutions:
1) mass of 1 mole of pennies
Data: mass of 1 penny = 2.50 g
1 mole = 6.022 * 10^ 23 units
Proportion:
1 penny 6.022 * 10^23 penny
-------------- = ----------------------------
2.50 g x
Solve: x = 6.022 * 10^23 penny * 2.50g / 1 penny = 15.055* 10^23
Since 2.50 has 3 significant figures, the answer must use 3 significant figures => x = 15.1 * 10^ 23 g = 1.51 * 10^24 g
Answer: 1 mol of pennies have a mass of 1.51 * 10^24 g
2) How many moles of pennies have a mass equal to the same mass of the Moon
Convert the mass of the Moon grams: 7.35 * 10^22 kg = 7.35 * 10^ 25 g
1 mol x
---------------------- = ----------------------
1.51 * 10^ 24g 7.35 * 10^ 25 g
=> x = 7.35 * 10^ 25 g * 1 mol / (1.51 * 10^24 g)= 48.7 mol
Answer: 48.7 mol
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Explanation:
The observation of student was that thermometer reading changed from 27°C to 35°C which indicates that temperature of the beaker solution rose after reaction due to release of heat during reaction as a product.
Those chemical reactions which gives heat energy as a product into their surrounding are categorized as exothermic reactions. During the course of these reaction temperature of the surroundings also increased.
So, this means that reaction between silver nitrate and copper wire is an exothermic reaction.
Three ways that the student could speed up the reaction :
- By adding catalyst to the reaction.
- By decreasing the temperature.
- By increasing the concentration of silver nitarte solution.
Procaine hydrochloride ( = 272.77 g/mol) is used as a local anesthetic. Calculate the molarity of a 4.666 m solution which has a density of 1.1066 g/ml.
molarity = Moles of solute / volume of solution
Molarity = m d / [ 1 + (mW / 1000)]
Molarity = 4.666 X 1.1066 / [ 1 + (4.666 X 272.77 / 1000)]
Molarity = 5.16 / 2.272= 2.271 M
To determine the Keq, we need the chemical reaction in the system. In this case it would be:
CO + 2H2 = CH3OH
The Keq is the ration of the amount of the product and the reactant. We use the ICE table for this. We do as follows:
CO H2 CH3OH
I .42 .42 0
C -0.13 -2(0.13) 0.13
-----------------------------------------------
E = .29 0.16 0.13
Therefore,
Keq = [CH3OH] / [CO2] [H2]^2 = 0.13 / 0.29 (0.16^2)
Keq = 17.51