0.448 moles of ions will form when a 42.66-gram sample of magnesium chloride is dissolved in water (option A).
<h3>How to calculate number of moles?</h3>
According to this question, when magnesium chloride (MgCl2) dissolves in water, it dissociates into magnesium ions and chloride ions as follows:
MgCl2(aq) ⟶ Mg2+(aq) + Cl−(aq)
However, if a 42.66-gram sample of magnesium chloride is dissolved in water, this means that 42.66g/molecular mass of MgCl2 will be the number of moles of the ionic products.
molecular mass of MgCl2 = 95.3g/mol
moles = 42.66g ÷ 95.3g/mol = 0.448mol
Therefore, 0.448 moles of ions will form when a 42.66-gram sample of magnesium chloride is dissolved in water.
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Average atomic mass is =1.11 u
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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
Question 17:
False; cutting hair would change what it looks like but, braiding it keeps it the same substance it is.
Question 18 :
My best guess would either be A or D. I would lean more towards D because if there are different mixtures then it depends on what you are mixing.
Hope it helps in some way. <3