Answer:
 I would try but i just need points good luck tho
  
        
             
        
        
        
Energy, Temperature, and Changes of State
Matter either loses or absorbs energy when it changes from one state to another. For example, when matter changes from a liquid to a solid, it loses energy. The opposite happens when matter changes from a solid to a liquid.
 
        
             
        
        
        
Answer:
11.45kcal/g
2.612 × 10³ kcal
Explanation:
When a compound burns (combustion) it produces carbon dioxide and water. The combustion of 2-methylheptane can be represented by the following balanced equation:
2 C₈H₁₈ + 25 O₂ ⇄ 16 CO₂ + 18 H₂O
It releases  1.306 × 10³ kcal every 1 mol of C₈H₁₈ that is burned.
<em>What is the heat of combustion for 2-methylheptane in kcal/gram?</em>
We know that the molar mass of C₈H₁₈ is 114.0g/mol. Then, using proportions:

<em>How much heat will be given off if molar quantities of 2-methylheptane react according to the following equation? 2 C₈H₁₈ + 25 O₂ ⇄ 16 CO₂ + 18 H₂O</em>
In this equation we have 2 moles of C₈H₁₈. So,

 
        
             
        
        
        
1.Calculate the number of mole of O2: 48/32=1.5 mol
2.Calculate the number of mole of H2 by mole ratio: 1.5 x 1/2=0.75 mol
3.Calculate the answer:
0.75 x 2=1.5g
        
             
        
        
        
 In plants, these energy factories are called chloroplasts. They collect energy from the sun and use carbon dioxide and water in the process called photosynthesis to produce sugars. Animals can make use of the sugars provided by the plants in their own cellular energy factories, the mitochondria.