Q

What prevents the gravity of the sun to pull all of the planets towards it?(1 point)

GuDViN [60]

The planets speed as they orbit the sun

6 0

2 years ago

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Given the following data:

bagirrra123 [75]

$176.0 \; \text{kJ} \cdot \text{mol}^{-1}$

As long as the equation in question can be expressed as the sum of the three equations with known enthalpy change, its $\Delta H$ can be determined with the Hess's Law. The key is to find the appropriate coefficient for each of the given equations.

Let the three equations with $\Delta H$ given be denoted as (1), (2), (3), and the last equation (4). Let $a$ , $b$ , and $c$ be letters such that $a \times (1) + b \times (2) + c \times (3) = (4)$ . This relationship shall hold for all chemicals involved.

There are three unknowns; it would thus take at least three equations to find their values. Species present on both sides of the equation would cancel out. Thus, let coefficients on the reactant side be positive and those on the product side be negative, such that duplicates would cancel out arithmetically. For instance, $3 + (-1) = 2$ shall resemble the number of $\text{H}_2$ left on the product side when the second equation is directly added to the third. Similarly

$\text{NH}_4 \text{Cl} \; (s)$ : $-2 \; a = 1$
$\text{NH}_3\; (g)$ : $-2 \; b = -1$
$\text{HCl} \; (g)$ : $2 \; c = -1$

Thus

$a = -1/2\\b = 1/2\\c = -1/2$ and

$-\frac{1}{2} \times (1) + \frac{1}{2} \times (2) - \frac{1}{2} \times (3)= (4)$

Verify this conclusion against a fourth species involved- $\text{N}_2 \; (g)$ for instance. Nitrogen isn't present in the net equation. The sum of its coefficient shall, therefore, be zero.

$a + b = -1/2 + 1/2 = 0$

Apply the Hess's Law based on the coefficients to find the enthalpy change of the last equation.

$\Delta H _{(4)} = -\frac{1}{2} \; \Delta H _{(1)} + \frac{1}{2} \; \Delta H _{(2)} - \frac{1}{2} \; \Delta H _{(3)}\\\phantom{\Delta H _{(4)}} = -\frac{1}{2} \times (-628.9)+ \frac{1}{2} \times (-92.2) - \frac{1}{2} \times (184.7) \\\phantom{\Delta H _{(4)}} = 176.0 \; \text{kJ} \cdot \text{mol}^{-1}$

3 0

3 years ago

Help me, it’s pretty easy science moon stuff !

trasher [3.6K]

Hello :)
Based on the information I received reading the picture, the answer should be “B”

Explanation: if I am wrong I’m very sorry. But that should be the answer

8 0

2 years ago

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2 Points

levacccp [35]

B aaaaaaaaaaassaaaaaaaaaaaaaaaaaaaaaaaaaaaaAaaaaaaaaaaaa

4 0

3 years ago

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identify the correct practices when setting up the condenser for a reflux system. select one or more:

erastovalidia [21]

The correct practices when setting up the condenser for a reflux system are option(c)and (d)i.e, to Grease the joint between the flask and the condenser and Align the flask so that the condenser is vertical.

A condenser's purpose is to transfer heat from a working fluid—in a steam power plant, for instance, water—to a secondary fluid or the ambient air. The effective heat transfer that takes place during phase shifts, in this case during the condensation of vapor into a liquid, is what powers the condenser.

A condenser is a heat exchanger used in heat transfer systems to cool a gaseous substance so that it condenses into a liquid condition. By doing this, the substance releases its latent heat and transfers it to the environment. On the back of a refrigerator, the condenser is located and is probably pretty dusty. The refrigerant cools down within and condenses, changing back from a gas to a liquid.

Learn more about condenser here:

https: //brainly.com/question/15563071

#SPJ4

The complete question is:

Identify the correct practices when setting up the condenser for a reflux system.

Select one or more:

-Clip the stopper in the top of the condenser.

-Start the heat before the condenser water to test the set-up.

-Grease the joint between the flask and the condenser.

-Align the flask so that the condenser is vertical.

6 0

1 year ago