62.5 mL is prepare .
What is molarity?
Molar concentration is a unit of measurement for the concentration of a chemical species, specifically a solute, in a solution, expressed as the amount of substance per unit volume of solution. The most often used unit for molarity in chemistry is the number of moles per litre, denoted by the unit symbol mol/L or mol/dm3 in SI units.
Molarity of the stock solution as 0.100 M
Volume of the dilute solution as 250 mL
Molarity of dilute solution as 0.0250 M
We are required to calculate the Volume of the stalk solution.
Taking the volume and molarity of the stock solution to be V₁ and M₁ respectively, and volume and molarity of the dilute solution to be V₂ and M₂ respectively.
We are going to use the dilution formula;
According to the dilution formula, M₁V₁ = M₂V₂
Rearranging the formula;
V₁ = M₂V₂ ÷ M₁
= (0.025 M × 0.25 L) ÷ 0.100 M
= 0.0625 L
But, 1 L = 1000 mL
V₁ = 62.5 mL
Therefore, the volume of the stock solution is 62.5 mL
Learn more about molarity from given link
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Answer:
12.99
Explanation:
<em>A chemist dissolves 716. mg of pure potassium hydroxide in enough water to make up 130. mL of solution. Calculate the pH of the solution. (The temperature of the solution is 25 °C.) Be sure your answer has the correct number of significant digits.</em>
Step 1: Given data
- Mass of KOH: 716. mg (0.716 g)
- Volume of the solution: 130. mL (0.130 L)
Step 2: Calculate the moles corresponding to 0.716 g of KOH
The molar mass of KOH is 56.11 g/mol.
0.716 g × 1 mol/56.11 g = 0.0128 mol
Step 3: Calculate the molar concentration of KOH
[KOH] = 0.0128 mol/0.130 L = 0.0985 M
Step 4: Write the ionization reaction of KOH
KOH(aq) ⇒ K⁺(aq) + OH⁻(aq)
The molar ratio of KOH to OH⁻is 1:1. Then, [OH⁻] = 0.0985 M
Step 5: Calculate the pOH
We will use the following expression.
pOH = -log [OH⁻] = -log 0.0985 = 1.01
Step 6: Calculate the pH
We will use the following expression.
pH + pOH = 14
pH = 14 - pOH = 14 -1.01 = 12.99
Answer:
2.15
Explanation:
For this question, we have to remember the <u>pH formula</u>:
![pH~=~-Log[H_3O^+]](https://tex.z-dn.net/?f=pH~%3D~-Log%5BH_3O%5E%2B%5D)
By definition, the pH value is calculated when we do the -Log of the concentration of the <u>hydronium ions</u> (
). So, the next step is the calculation of the <u>concentration</u> of the hydronium ions. For this, we have to use the <u>molarity formula</u>:
We already know the number of moles (0.0231 moles) and the volume (3.33 L). So, we can plug the values into the molarity formula:
With this value, now we can calculate the pH value:
![pH~=~-Log[0.00693~M]~=~2.15](https://tex.z-dn.net/?f=pH~%3D~-Log%5B0.00693~M%5D~%3D~2.15)
<u>The pH would be 2.15</u>
I hope it helps!
<span>Hydrogen bonds are
approximately 5% of the bond strength of covalent bonds, for example (C-C or C-H
bonds).
Hydrogen bonds strength in water is approximately 20
kJ/mol, strenght of carbon-carbon bond is approximately 350 kJ/mol
and strengh of carbon-hydrogen bond is approximately 340 kJ/mol.
20 kJ/350 kJ = 0,057 = 5,7 %.</span>
The process by which rocks are broken down to form soil is called weathering. It is divided into 3 types, physical, chemical and biological weathering.
Physical weathering is the process by which rocks are broken down as a result of physical agitations. It is also called mechanical weathering and during this process the chemical nature of the rock is not affected. Biological weathering has to do with the weakening of rocks and their eventual disintegration as a result of plants and animals activities. Chemical weathering refers to the disintegration of the rock particles as a result of chemical reactions.
