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
<u>Answer:</u> The mass of water that should be added in 203.07 grams
<u>Explanation:</u>
To calculate the molality of solution, we use the equation:

Where,
m = molality of barium iodide solution = 0.175 m
= Given mass of solute (barium iodide) = 13.9 g
= Molar mass of solute (barium iodide) = 391.14 g/mol
= Mass of solvent (water) = ? g
Putting values in above equation, we get:

Hence, the mass of water that should be added in 203.07 grams
Explanation:
Given parameters:
Initial volume V1 = 200cm³
Initial temperature = 60°C
Final temperature = 120°C
Unknown:
Final volume = ?
Solution:
According to Charles law, at constant pressure, the volume of a given mass of gas is directly proportional to temperature.
mathematically;

1 and 2 are the initial and final states
V is the volume and T is the temperature
convert the temperature to kelvin
T1 = 60 + 273 = 333K
T2 = 120 + 273 = 393K
Input the parameters;

final volume is 236cm³
learn more:
Boyle's law brainly.com/question/8928288
#learnwithBrainly
Heat always flows from hot to cold.