To find this, we will use this formula:
Molar mass of element
------------------------------------ x 100
Molar mass of compound
So, first lets calculate the mass of the compound as a whole. We use the atomic masses on the periodic table to determine this.
Ca: 40.078 g/mol
N2 (there is two nitrogens): 28.014 g/mol
O6 (there are six nitrogens: 3 times 2): 95.994 g/mol
When we add all of those numbers up together, we get 164.086. That is the molar mass for the whole compound. However, we are trying to figure out what percent of the compound oxygen makes up. From the molar mass, we know that 95.994 of the 164.086 is oxygen. Lets plug those numbers into our equation!
95.994
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164.086
When we divide those two numbers, we get .585. When we multiply that by 100, we get 58.5.
So, the percent compostition of oxygen in Ca(NO3)2, or, calcium nitrate, is 58.5%.
The answer is a change in internal energy causes work to be done and heat to flow into the system.
<u>Explanation:</u>
- The first law of thermodynamics is a similar version of the law of conservation of energy where the energy can neither be created nor be destroyed, it can be transformed from one form to the other.
- It also defines that the work is done and heat flowing into the system is due to the change in internal energy. The sum of all energy including kinetic and potential energy except the displaced energy to the surrounding is known as internal energy.
- ΔU represents the change in internal energy of the system, Q represents the net heat transferred into the system, and W represents the net work done by the system. So +ve Q adds energy to the system and =ve W takes energy from the system. Thus ΔU=Q−W.
Answer:
3224 kJ/mol
Explanation:
The combustion of benzoic acid occurs as follows:
C₇H₆O₂ + 13/2O₂ → 7CO₂ + 3H₂O + dE
The change in temperature in the reaction is the change due the energy released, that is:
3.256K * (10.134kJ / K) = 33.00kJ are released when 1.250g reacts
To find the heat released per mole we have to find the moles of benzoic acid:
<em>Moles benzoic acid -Molar mass: 122.12g/mol-:</em>
1.250g * (1mol / 122.12g) = 0.0102 moles
<em />
The dE combustion per mole of benzoic acid is:
33.00kJ / 0.0102moles =
<em>3224 kJ/mol </em>
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