Question

If the following solutions are mixed, is the resulting solution acidic, basic, or neutral?125.0 mL of 0.100 M HNO3 and 80.0 mL of 0.0750 M Ca (OH) 2

Answer 1

Step 1

Information provided:

125.0 mL of 0.100 M HNO3

80.0 mL of 0.0750 M Ca(OH)2

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Step 2

Molarity is defined as follows

`Molarity\text{ \lparen mol/L or M\rparen = }\frac{Moles\text{ of solute}}{Volume\text{ of solution \lparen L\rparen}}`

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Step 3

The number of moles in addition from each solution:

HNO3)

125.0 mL = 0.125 L

(1 L = 1000 mL)

Moles HNO3 = Molarity x Volume (L)

Moles HNO3 = 0.100 M x 0.125 L = 0.0125 moles

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Ca(OH))

80.0 mL = 0.080 L

Moles = 0.0750 M x 0.080 L = 6x10^-3 moles

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Step 4

HNO3 and Ca(OH)2 are strong compounds, so:

HNO3 => H+ + NO3-

0.0125 moles 0.0125 moles 0.0125 moles

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Ca(OH)2 => Ca2+ + 2 OH-

6x10^-3 moles 6x10^-3 moles 2 x 6x10^-3 moles = 0.012 moles

Number of moles of H+ = 0.0125 moles

Number of moles of OH- = 0.012 moles

It appears to be neutral but according to our calculation: The number of moles of H+ = 0.0125 moles > Number of moles of OH- = 0.012 moles

So, the mixture is acidic

Answer: acidic