The image below represents which of the following (Check all that apply):

If charges flow very slowly through a metal, why does it not require several hours for a light to come on when you throw a switc

Harlamova29_29 [7]

T<span>he charges themselves may not move fast, but the force upon them does. The electric field set up by the battery or generator propagates through the wires at the speed of light.

Thank you for posting your question here at brainly. I hope the answer will help you. Feel free to ask more questions.
</span>

6 0

2 years ago

2CH4(g)⟶C2H4(g)+2H2(g)

Rasek [7]

Answer : The enthalpy change for the reaction is, 201.9 kJ

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

The balanced reaction of $CH_4$ will be,

$2CH_4(g)\rightarrow C_2H_4(g)+2H_2(g)$ $\Delta H^o=?$

The intermediate balanced chemical reaction will be,

(1) $CH_4(g)+2O_2(g)\rightarrow CO_2(g)+2H_2O(l)$ $\Delta H_1=-890.3kJ$

(2) $C_2H_4(g)+H_2(g)\rightarrow C_2H_6(g)$ $\Delta H_2=-136.3kJ$

(3) $2H_2(g)+O_2(g)\rightarrow 2H_2O(l)$ $\Delta H_3=-571.6kJ$

(4) $2C_2H_6(g)+7O_2(g)\rightarrow 4CO_2(g)+6H_2O(l)$ $\Delta H_4=-3120.8kJ$

Now we will multiply the reaction 1 by 2, revere the reaction 2, reverse and half the reaction 3 and 4 then adding all the equations, we get :

(1) $2CH_4(g)+4O_2(g)\rightarrow 2CO_2(g)+4H_2O(l)$ $\Delta H_1=2\times (-890.3kJ)=-1780.6kJ$

(2) $C_2H_6(g)\rightarrow C_2H_4(g)+H_2(g)$ $\Delta H_2=-(-136.3kJ)=136.3kJ$

(3) $H_2O(l)\rightarrow H_2(g)+\frac{1}{2}O_2(g)$ $\Delta H_3=-\frac{1}{2}\times (-571.6kJ)=285.8kJ$

(4) $2CO_2(g)+3H_2O(l)\rightarrow C_2H_6(g)+\frac{7}{2}O_2(g)$ $\Delta H_4=-\frac{1}{2}\times (-3120.8kJ)=1560.4kJ$

The expression for enthalpy of the reaction will be,

$\Delta H^o=\Delta H_1+\Delta H_2+\Delta H_3+\Delta H_4$

$\Delta H=(-1780.6kJ)+(136.3kJ)+(285.8kJ)+(1560.4kJ)$

$\Delta H=201.9kJ$

Therefore, the enthalpy change for the reaction is, 201.9 kJ

5 0

1 year ago

A gas occupies a volume of 72 ml at 400 k and 800 torr. if the temperature drops to 200 k and the pressure changes to 400 torr,

satela [25.4K]

We are tasked to solve for the volume of the gas that occupies when pressure and temperature changes to 400 Torr and 200 Kelvin from Torr and 400 Kelvin. We can use ideal gas law assuming constant gas composition and close system. The solution is shown below:
P1V1 / T1 = P2V2 / T2
V2 = P1V1T2 / T1P2
V2 = 800*72*200 / 400*400
V2 = 72 ml

The answer for the volume is 72 ml.

7 0

2 years ago

The image shows a wheel that's wound up and released. The wheel moves up and down as shown. Identify the position of the wheel w

Lesechka [4]

Explanation:

Since the wheel moves up and down, the position that represents the potential energy is that which has the maximum height from the ground.

Potential energy is the energy at rest of a body.

It is given as:

Potential energy = m x g x h

m is the mass of the body

g is the acceleration due to gravity

h is the height of the body

We can see that mass and height are directly related to the potential energy a body exerts.

The higher the wheel from ground, the higher its potential energy.

learn more

Potential energy brainly.com/question/10770261

#learnwithBrainly

7 0

2 years ago

12. Penny can knit 4 rows of a sweater in 5

Evgesh-ka [11]

Answer:

6.25 hours

Explanation:

From the question;

Penny can knit 4 rows in 5 minutes

We need to determine the time it will take for her to knit 300 rows

4 rows = 5 minutes

300 rows = ?

= (300 × 5 ) ÷ 4

= 375 minutes

But, 1 hour = 60 minutes

Therefore;

= 375 ÷ 60

= 6.25 hours

Thus, it will take penny 6.25 hours to knit 300 rows

8 0

1 year ago