Answer:
Q = 2.60 •
J
Explanation:
Our specific heat capacity equation is:
Q = mC∆T
Q is the energy in joules.
m is the mass of the substance.
∆T is the temperature chance.
Let's plug in what we know.
- We have 76.0 g of octane
- The specific heat capacity of octane is 2.22 J/(g•K)
- The temperature increases from 10.6º to 26.0º (a 15.4º increase)
Q = 76.0(2.22)(15.4)
Multiply.
Q = 2598.288
We want three significant figures.
Q = 2.60 • 
or
Q = 2590 J
Hope this helps!
Answer:
0.2598 M
Explanation:
Molarity is mol/L, so we have to convert the grams to moles and the mL to L. To convert between grams and moles you need the molar mass of the compound, which is 36.46g/mol.



Round to the lowest number of significant figures = 0.2598 M
The combustion of methane, CH4, releases 890.4 kJ/mol. That is, when one mole of methane is burned, 890.4 kJ are given off to the surroundings. This means that the products have 890.4 kJ less than the reactants.
Answer: 12.18 u
Explanation: The average atomic mass of an element is calculated by taking the weighted average of the atomic masses of its stable isotopes.
In other words, each stable isotope will contribute to the average mass of the element proportionally to its abundance.