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puteri [66]
3 years ago
8

By using the following reactions, calculate the heat of combustion of pentane:

Chemistry
1 answer:
Sergio [31]3 years ago
6 0
To answer this problem, we use Hess' Law to calculate the overall enthalpy of the reactions. The goal is to add all the reactions such that the final reaction is C<span>5H12 (g) + 8O2 (g) → 5CO2 (g) + 6H2O (l) through cancellation adn multiplication. The first equation is multiplied by 5, the second one is multiplied by 6 and the third one is reversed. The final answer is -3538 J or -3.54 x10^3 kJ.</span>
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At the top of a hill, an athlete on a skateboard has X joules of mechanical energy. How much mechanical energy will she have at
ExtremeBDS [4]

If an athlete has X joules of mechanical energy at the top of the hill, he will have the same X amount of energy at the bottom of the hill.

<h3>What is mechanical energy?</h3>

Mechanical energy is the addition of kinetic and potential energy. It can be either kinetic or potential energy.

It is the energy possessed by the position or the motion of the body.

It is the energy present to perform any work.

So, the athlete will have X joule of energy at the top and bottom of the hill.

Thus, the correct option is a, X joules.

Learn more about mechanical energy

brainly.com/question/20030300

5 0
2 years ago
Thanks for the help :) Question attached below:
Alekssandra [29.7K]

• Take a look at the steps below to see how to balance this equation. Let's start by writing the unbalanced equation given the information.

Unbalanced Equation : C₃H₈ (g) + O₂ (g) → CO₂ (g) + H₂O (g) ,

Start by Balancing the Carbons : C₃H₈ (g) + O₂ (g) → 3CO₂ (g) + H₂O (g)

Now let's balance the Hydrogen : C₃H₈ (g) + O₂ (g) → 3CO₂ (g) + 4H₂O (g)

Balancing the Oxygen : C₃H₈ (g) + 5O₂ (g) → 3CO₂ (g) + 4H₂O (g)

Balanced Equation : C₃H₈ (g) + 5O₂ (g) → 3CO₂ (g) + 4H₂O (g)

• Let's apply dimensional analysis here,

0.7 L propane × (5 liters Oxygen / 1 liter Propane) = 3.5 Liters of Oxygen

•  Similarly we can identify the liters of carbon dioxide produced in the reaction,

0.7 L propane × (3 liters Carbon Dioxide / 1 liter Propane) = 2.1 Liters of Carbon Dioxide

• 0.7 L propane × (4 liter water vapor / 1 liter propane ) = 2.8 Liters of Water Vapor

7 0
3 years ago
The rate constant for the decomposition reaction of H2O2 is 3.66 × 10−3 s−1 at a particular temperature. What is the concentrati
Pepsi [2]

Answer:  3.72 M

Explanation:

Expression for rate law for first order kinetics is given by:

t=\frac{2.303}{k}\log\frac{a}{a-x}

where,

k = rate constant = 3.66\times 10^{-3}s^{-1}

t = age of sample = 15.0 minutes

a = let initial amount of the reactant  = 10.0 M

a - x = amount left after decay process = ?

15.0\times 60s=\frac{2.303}{3.66\times 10^{-3}}\log\frac{10.0}{(a-x)}

\log\frac{100}{(a-x)}=1.43

\frac{100}{(a-x)}=26.9

(a-x)=3.72M

The concentration of H_2O_2 in a solution after 15.0 minutes have passed is 3.72 M

7 0
3 years ago
While following the Dumas method, a student assumes that the contents of the container are the same temperature as the water bat
Nataliya [291]

Answer:

A

Explanation:

the Molar mass will be smaller as the content of the container is not directly proportional to the temperature of the water bath.

5 0
3 years ago
PLEAS HELP ASAP!!! Which of these statements best explains why the running costs for geothermal power plants are very low?
natima [27]
Correct answer is <span>Fuels do not have to be purchased to generate power.</span>
4 0
3 years ago
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