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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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Answer:
Explanation:
Hello!
In this case, since these calorimetry problems are characterized by the fact that the calorimeter absorbs the heat released by the combustion of the substance, we can write:
Thus, given the temperature change and the total heat capacity, we obtain the following total heat of reaction:
Now, by dividing by the moles in 1.04 g of cyclopropane (42.09 g/mol) we obtain the enthalpy of combustion of this fuel:
Best regards!
Answer:
The H+ (aq) concentration of the resulting solution is 4.1 mol/dm³
(Option C)
Explanation:
Given;
concentration of HA, 
= 6.0mol/dm³
volume of HA, 
= 25.0cm³, = 0.025dm³
Concentration of HB, 
= 3.0mol/dm³
volume of HB, 
= 45.0cm³ = 0.045dm³
To determine the H+ (aq) concentration in mol/dm³ in the resulting solution, we apply concentration formula;
where;
is initial concentration
is initial volume
is final concentration of the solution
is final volume of the solution
Therefore, the H+ (aq) concentration of the resulting solution is 4.1 mol/dm³
Answer:
When the two atoms move towards each other a compound is formed by sharing electron pairs supplied by each of the atoms to enable them have the stable 8 (octet) valency electrons in their outermost shell
Explanation:
The electronic configuration of the given element can be written as follows;
1s²2s²2p⁴
The given electronic configuration is equivalent to that of oxygen, therefore, we have;
The number of electrons in the valence shell = 2 + 4 = 6 electrons
Therefore, each atom requires 2 electrons to complete its 8 (octet) electrons in the outermost shell
When the two atoms move towards each other, they react and combine to form a compound by sharing 4 electrons, 2 from each atom, such that each atom can have an extra 2 electrons in its outermost orbit in the newly formed compound and the stable octet configuration is attained by each of the atoms in the newly formed compound.
