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3 years ago

What is the ph of a solution with a hydroxyl ion (oh-) concentration of 10-10 m?

1 answer:

7 0

PH is the potential of hydrogen, pH provides a measure of the concentration of hydrogen ion while pOH scale provides the concentration of OH- ions.
pH denotes the negative logarithm of concentration of hydrogen while pOH denotes the negative logarithm of the concentration OH- ions.
Therefore; in this case the pOH= -log (OH-)
= - log (10^-10)
= 10
If the pOH is 10 then the pH of the solution will be 4

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A sample of pure calcium fluoride with a mass of 15.0 g contains 7.70 g of calcium. how much calcium is contained in 45.0 g of c

kolbaska11 [484]

In a sample of pure calcium fluoride of mass 15.0 g, 7.70 g of calcium is present. First convert the mass into number of moles as follows:

$n=\frac{m}{M}$

Here, m is mass and M is molar mass.

Molar mass of Ca is 40 g/mol, putting the values,

$n=\frac{7.70 g}{40 g/mol}=0.1925 mol$

Similarly, molar mass of $CaF_{2}$ is 78.07 g/mol thus, number of moles will be:

$n=\frac{15.0 g}{78.07 g/mol}=0.1921 mol$ .

Thus, 0.1921 mol of $CaF_{2}$ have 0.1925 mol of Ca, or 1 mole of $CaF_{2}$ will have approximately 1 mole of Ca.

Now, mass of Ca needs to be calculated in 45.0 g of $CaF_{2}$ . Converting mass into number of moles first,

$n=\frac{45.0 g}{78.07 g/mol}=0.5764 mol$

Thus, number of moles of Ca will also be 0.5764 mol, converting number of moles into mass,

$m=n\times M=0.5764 mol\times 40 g/mol=23.06 g$

Therefore, mass of Ca will be 23.06 g.

6 0

3 years ago

How many valence electrons does magnesium (Mg) have?Question options:A) 6B) 2C) 12D) 0

wel

INFORMATION:

We must find the number of valence electrons for magnesium

STEP BY STEP EXPLANATION:

In order to know the number of valence electrons for Mg, we need to locate the element in the periodic table

Since Mg is in the second group of the periodic table, it has two valence electrons.

ANSWER:

B) 2

4 0

1 year ago

An IV bag is labeled as 0.800% w/w sodium chloride in water solution with a density of 1.036g/mL. What is the concentration of s

Goryan [66]

Answer:

[NaCl] = 0.14 M

[NaCl] = 0.14 m

Mole fraction of NaCl → 2.48×10⁻³

Explanation:

This is a problem of concentration.

0.8% w/w means that in 100 g of solution, we have 0.8 g of solute, in this case NaCl.

Let's determine the volume with the density.

Solution density = Solution mass / Solution volume

1.036 g/mL = 100 g / Solution volume

Solution volume = 100 g / 1.036 g/mL → 96.5 mL

Let's calculate molarity (mol/L)

We convert the mass to moles (mass / molar mass)

0.8 g / 58.45 g/mol = 0.0137 moles

We must convert the volume of solution to L.

Molarity is mol/L, moles of solute in L of solution.

96.5 mL . 1L/1000 mL = 0.0965 L

0.0137 mol / 0.0965 L = 0.14 M

Let's determine molality and mole fraction.

Molality are moles of solute in 1 kg of solvent (mol/kg)

Mass of solution = Mass of solute + Mass of solvent

100 g = 0.8 g + Mass of solvent

100 g - 0.8 g = Mass of solvent → 99.2 g

Then, we must convert the mass of solvent to kg

99.2 g . 1kg / 1000 g = 0.0992 kg

Molality: 0.0137 mol / 0.0992 kg → 0.14 m

Mole fraction → moles of solute / moles of solute + moles of solvent

Let's find out the moles of solvent ( mass / molar mass)

99.2g / 18 g/mol = 5.511 mol

Total moles = 5.511 + 0.0137 → 5.5247 moles

Mole fraction = 0.0137 / 5.5247 → 2.48×10⁻³

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3 years ago

Carbonic acid is an important agent involved in rock and mineral dissolution. How is carbonic acid formed?

Vitek1552 [10]

Answer:

Carbonic acid a type of weak acid formed from the dissolving of carbon dioxide in water.

Explanation:

The chemical formula of carbonic acid is H2CO3. Its structure consists of a carboxyl group with two hydroxyl groups connected. As a weak acid, it partially ionizes, dissociates or rather, breaks apart, in a solution.

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3 years ago

What is the name of the polyatomic ion in the compound na2o2?

EastWind [94]

Sodium peroxide is the answer!

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3 years ago