How does climate determine the organisms that live in a biome

A chemistry student must write down in her lab notebook the concentration of a solution of potassium chloride. The concentration

DerKrebs [107]

Answer:

3.65 g / ml correct to 3 sig. fig.

Explanation:

The computation of the concentration required is shown below:

As we know that

[A] = mass of solute ÷ volume of solution

Before that first find the mass of solute

Given that

Initial weight = 5.55g

And,

Final weight = 92.7 g

So,

Mass of KCl is

= 92.7 - 5.55

= 87.15 g ~ 87.2 g

Now the KCi is fully dissolved, so the volume is 23.9 ml

So, concentration is

= 87.2 g ÷ 23.9 ml

= 3.65 g / ml correct to 3 sig. fig.

6 0

3 years ago

What is the concentration of H+ in 0.0025 M HClO4? What is the pH of the solution? What is the OH− concentration in the solution

alexandr402 [8]

Answer:

A. The concentration of H+ is 0.0025 M

B. The pH is 2.6

C. The concentration of OH- is 3.98x10^-12 M

Explanation:

We'll begin by writing the balanced

dissociation equation of HClO4. This is illustrated below:

HClO4 —> H+ + ClO4-

A. Determination of the concentration of H+ in 0.0025 M HClO4. This is illustrated below:

From the balanced equation above,

1 mole of HClO4 produced 1 mole of H+.

Therefore, 0.0025 M of HClO4 will also produce 0.0025 M of H+.

The concentration of H+ is 0.0025 M

B. Determination of the pH.

The pH of the solution can be obtained as follow:

The concentration of H+, [H+]

= 0.0025 M

pH =?

pH = - log [H+]

pH = - log 0.0025

pH = 2.6

C. Determination of the concentration of OH-

To obtain the concentration of OH-, we must first calculate the pOH of the solution. This is illustrated below:

pH + pOH = 14

pH = 2.6

pOH =?

pH + pOH = 14

2.6 + pOH = 14

Collect like terms

pOH = 14 - 2.6

pOH = 11.4

Now, we can calculate the concentration of the OH- as follow:

pOH = - Log [OH-]

pOH = 11.4

11.4 = - Log [OH-]

- 11.4 = log [OH-]

[OH-] = anti log (- 11.4)

[OH-] = 3.98x10^-12 M

8 0

3 years ago

A sodium hydroxide solution is made by mixing 8.70 g NaOH with 100 g of water. The resulting solution has a density of 1.087 g/m

Ahat [919]

Answer:

Mass fraction = 0.08004

Mole fraction = 0.0377

Explanation:

Given, Mass of NaOH = 8.70 g

Mass of solution = 8.70 + 100 g = 108.70 g

$Mass\ fraction\ of\ NaOH=\frac {8.70}{108.70}$ = 0.08004

Molar mass of NaOH = 39.997 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{8.70\ g}{39.997\ g/mol}$

$Moles\ of\ NaOH= 0.2175\ mol$

Given, Mass of water = 100 g

Molar mass of water = 18.0153 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{100\ g}{18.0153\ g/mol}$

$Moles\ of\ water= 5.5508\ mol$

So, according to definition of mole fraction:

$Mole\ fraction\ of\ NaOH=\frac {n_{NaOH}}{n_{NaOH}+n_{water}}$

$Mole\ fraction\ of\ NaOH=\frac {0.2175}{0.2175+5.5508}=0.0377$

3 0

3 years ago

Write an equilibrium equation that shows bisulfate acting as a weak acid in water.

NemiM [27]

Answer:

Explanation:

Bisulphate ion is a weak acid as it can form hydronium ion in water .

HSO₄⁻ + H₂O ⇄ SO₄⁻² + H₃O⁺

The equilibrium constant of this reaction is very small , hence bisulphate ion is very weak acid.

4 0

3 years ago

A student wants to examine a substance by altering the bonds within its molecules. Which of the following properties of the subs

Marrrta [24]

Question is incomplete, the complete question is as follows:

A student wants to examine a substance by altering the bonds within its molecules. Which of the following properties of the substance should the student examine?

A. Toxicity, because it can be observed by altering the state of the substance

B. Boiling point, because it can be observed by altering the state of the substance

C. Toxicity, because it can be observed by replacing the atoms of the substance with new atoms

D. Boiling point, because it can be observed by replacing the atoms of the substance with new atoms

Answer:

B.

Explanation:

A student can examine a substance without altering the bonds within the molecules by examining its boiling point.

The boiling point is the property of a substance, at which the substance changes its state, which is from solid to liquid, liquid to gas and others. So, examining the boiling point will alter the bonds within the molecules as the state of substance will change.

Hence, the correct answer is "B".

6 0

3 years ago