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3 years ago

What is a chemical energy

1 answer:

8 0

Chemical energy is the potential of a chemical substance to undergo a transformation through a chemical reaction to transform other chemical substances. Examples include batteries, food, gasoline, and etc.

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A cup of hot coffee initially at 95 degrees C cools to 80 degrees C in 5 min while sitting in a room of temperature 21 degrees C

Oksana_A [137]

Answer:

When the temperature of the coffee is 50 °C, the time will be 20.68 mins

Explanation:

Given;

The initial temperature of the coffee T₀ = 95 °C

The temperature of the room = 21°C

Let T be the temperature at time of cooling t in mins

According to Newton's law of cooling;

$\frac{dT}{dt} \alpha (T-21)\\\\\frac{dT}{dt} = k (T-21)\\\\\frac{dT}{T-21} = kdt\\\\\int\limits {\frac{dT}{T-21}} = \int\limits kdt\\\\Log(T-21) =kt + Logc \\\\Log (\frac{T-21}{c} ) = kt\\\\T -21 = ce^{kt}\\\\At \ t = 0, T = 95\\\\95-21 = ce^0\\\\74 = c\\\\New, equation: T -21 = 74e^{kt}\\\\Again; when \ t= 5\ min, T = 80\\\\80 -21 = 74e^{5k}\\\\59 = 74e^{5k}\\\\e^{5k} = \frac{59}{74}\\\\ 5k = ln(\frac{59}{74})\\\\5k = -0.2265\\\\k = -0.0453$

When the temperature is 50 °C, the time t in min is calculated as;

$T -21 = 74e^{-0.0453t}\\\\50 -21 = 74e^{-0.0453t}\\\\29 = 74e^{-0.0453t}\\\\\frac{29}{74} = e^{-0.0453t}\\\\0.39189 = e^{-0.0453t}\\\\ln(0.39189 ) = {-0.0453t}\\\\-0.93677 = {-0.0453t}\\\\t = \frac{-0.93677}{-0.0453}\\\\ t = 20.68 \ mins$

Therefore, when the temperature of the coffee is 50 °C, the time will be 20.68 mins

4 0

3 years ago

What is the speed of a 1200 kg car moving<br> with a kinetic energy of 15 kJ?

Pepsi [2]

Answer:5m/s

Explanation:

Kinetic energy=ke=15kj=15x1000j=15000j

Mass=1200kg

Speed=√(2ke/m)

Speed=√(2x15000/1200)

Speed=√(30000/1200)

Speed=√(25)

Speed=5m/s

7 0

3 years ago

The initial concentration of N2O4 is 0.45M The system is heated and allowed to reach equilibrium. At equilibrium concentration o

Damm [24]

Answer : The value of equilibrium constant $K_c$ for the following reaction will be, 2.4

Explanation : Given,

Initial concentration of $N_2O_4$ = 0.45 M

Equilibrium concentration of $NO_2$ = 0.30 M

$K_c$ is defined as the equilibrium constant. It is defined as the ratio of concentration of products to the concentration of reactants.

The given balanced equilibrium reaction is,

$N_2O_4(g)\rightleftharpoons 2NO_2(g)$

As we know that the concentrations of pure solids are constant that means they do not change. Thus, they are not included in the equilibrium expression.

Actual concentration of $NO_2$ at equilibrium = $2\times 0.30M=0.6M$

Concentration of $N_2O_4$ at equilibrium = $[N_2O_4]-[NO_2]=0.45-0.30=0.15M$

The expression for equilibrium constant for this reaction will be,

$K_c=\frac{[NO_2]^2}{[N_2O_4]}$

Now put all the given values in this expression, we get :

$K_c=\frac{(0.6)^2}{(0.15)}$

$K_c=2.4$

Therefore, the value of equilibrium constant $K_c$ for the following reaction will be, 2.4

3 0

3 years ago

In three to five sentences, identify the acid, base, conjugate acid, and conjugate base. Use patterns in the periodic table to e

Oliga [24]

A conjugate acid is formed from the base by accepting a proton from the acid .

A conjugate base is obtained from the Brownstead - Lowry acid when it looses a proton while the conjugate acid is obtained from the Brownstead - Lowry base when it accepts a proton. In the Brownstead - Lowry sense, acid base reaction involves the loss or gain of a proton.

Consider the hypothetical reaction; AH + :B ⇄ BH + :A. The specie BH is the conjugate acid while the specie :B is the Brownstead - Lowry base . The specie :A is the conjugate base while the specie AH is the Brownstead - Lowry acid.

Learn more about conjugate acid: brainly.com/question/10468518

6 0

3 years ago

If a ball has a velocity of 18 m/s, how far does it travel in 15 seconds

Stolb23 [73]

Answer:

The answer is

Explanation:

To find the distance when given the velocity and time we use the formula

<h3>distance = velocity × time</h3>

From the question

velocity of the ball = 18 m/s

time = 15 s

So the distance is

distance = 18 × 15

We have the final answer as

Hope this helps you

7 0

3 years ago