A 72 kg athlete climbs a rope to a height of 12m. Calculate the increase in gravitational potential energy it has experienced.
Answer:
8467.2J
Explanation:
Given parameters: 
Mass of the athlete = 72kg 
Height of the climb  = 12m 
Unknown: 
Increase in gravitational potential energy it has experienced = ? 
Solution: 
Gravitational potential energy is the energy due to the position of a body. It is mathematically expressed as; 
   Gravitational potential energy  = m x g x h 
m is the mass
g is the acceleration due to gravity  = 9.8m/s² 
h is the height 
    Insert the parameters and solve; 
   Gravitational potential energy  = 72 x 9.8 x 12 
   GPE = 8467.2J
 
        
             
        
        
        
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,

 
        
             
        
        
        
Answer:
Kb = 

Explanation:
For a weak organic base, the formula to find  is given by:
 is given by:

where c is the concentration of base.
Here c= 

Substituting the above values in the formula,we get:

Hence:
Kb = 

 
        
             
        
        
        
It would be a chemical change.
Hope this helps!