What is the molar mass of K?

Use the solubility rules from the Lab 4 introduction and your knowledge of qualitative separation schemes from the lab to answer

cluponka [151]

Answer:

a13+a13

Explanation:

4 0

2 years ago

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

The pressure on 30 milliliters of an ideal gas increases from

Nana76 [90]

V1 = 30 mL

P1 = 760 torr

P2 = 1520 torr

V2 = ?

applying Boyle's Law

P1*V1 = P2*V2

760 torr * 30 mL = 1520 torr * V2

V2 = 760 torr * 30 mL / 1520 torr

( C ) is correct

8 0

3 years ago

A solution with a ph of 4 has _________ the concentration of h+ present compared to a solution with a ph of 5.

Marina CMI [18]

A solution with a pH of 4 has ten times the concentration of H⁺ present compared to a solution with a pH of 5.
pH is a numeric scale for the acidity or basicity of an aqueous solution. It is the negative of the base 10 logarithm of the molar concentration of hydrogen ions.
[H⁺] = 10∧-pH.
pH = 4 → [H⁺]₁ = 10⁻⁴ M = 0,0001 M.
pH = 5 → [H⁺]₂ = 10⁻⁵ M = 0,00001 M.
[H⁺]₁ / [H⁺]₂ = 0,0001 M / 0,00001 M.
[H⁺]₁ / [H⁺]₂ = 10.

7 0

2 years ago

CaCO3 For each of the following compounds, decide whether the compound's solubility in aqueous solution changes with pH. If the

Slav-nsk [51]

Answer:

Hello attached below is the data found in Aleks Data tab

answer :

i) N0

ii) N0

iii) YES , pH of highest solubility = 5

Explanation:

i) For CuBr

solubility does not change with pH hence answer = NO

ii) For MgCl2

solubility does not change with pH hence the answer = NO

iii) For Ba(OH) 2

Solubility does change with pH hence the answer = YES

and the pH at which the highest solubility will occur is = 5

attached below is the reason for the answers given

4 0

3 years ago