Which method of moving materials in and out of the cell requires energy.

When 0.25 moles of NH3 are produced according to the reaction below, how many moles of H2 must have reacted?

marissa [1.9K]

Answer:

Explanation:

by stoichiometry

nNH3/2=nH2/3

0.25/2=nH2/3

nH2=0.25×3/2

nH2=0.375 mol

so its 0.38 mol

6 0

3 years ago

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Which best describes the trends in electronegativity on the periodic table?

Wittaler [7]

Answer:

My bad i didnt mean to put that carry on.

Explanation:

7 0

3 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

Identify each of the following mixtures as either homogeneous or heterogeneous and as a solution, a suspension, or a colloid.

Sergeeva-Olga [200]

Blood.

Blood is heterogeneous because it has corpuscles (blood cells and platelets) physically suspended in blood plasma. Blood plasma and the corpuscles have different properties and can be separated by methods such as centrifugation. Also, blood is considered a colloid suspension because it has the properties of both a colloid and a suspension. This is because the blood plasma acts as a colloid. More so, if blood was left to settle,then the blood cells would collect at the bottom hence taking the characteristic of a suspension.

Salad dressing.

Depending on the type of salad, it can either be a heterogeneous or homogeneous mixture. If the salad dressing is only of vinegar or any other oil, then it is a homogenous mixture. However, if it involves a mixture of vinegar and other oils, pepper, herbs, and etcetera, then it is a heterogeneous mixture

4 0

3 years ago

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Magnesium reacts with a certain element to form a compound with the general formula MgX. What would the most likely formula be f

ziro4ka [17]

Answer:K2X

Explanation: Valency can be defined as the combining power of an element. It is the valency that dictates the value an element will have when writing a chemical formula for its compound.

MgX is a compound of magnesium and an element X. The valency of magnesium in most of its compound is +2. Now for the 2 to have been absent in the chemical formula, this shows that the element X itself have a valency if -2 for the valencies of both to have canceled out.

Now considering the element potassium, it is an alkaline metal belonging to group 1 of the periodic table. Hence, it is expected that it has a valency of +1

Forming a compound with element X means there would be an exchange of valencies between the two. We have established that x has a valency of -2. The formula of the compound thus formed by exchanging the valencies of both element would be K2X

7 0

2 years ago

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