«previous 10 of 14 | next Problem 10.110 Write a balanced equation for the react

Question

«previous 10 of 14 | next Problem 10.110 Write a balanced equation for the reaction Express your answer as a chemical equation. Identify all of the phases in your answer Sodium oxide, Na2 O, reacts with water to give NaOH. al xxbb Submit My Answers Give Up Incorrect; Try Again; 4 attempts remaining Check that you have properly identified all of the phases in your answer Part B What is the pH of the solution prepared by allowing 2.85 g of Na2O to react with 250.0 mL of water? Assume that there is no volume change Express your answer using three decimal places pH- Submit My Answers Give Up Part C How many milliliters of 0.0100 M HCl are needed to neutralize the NaOH solution prepared in the part B?

Explanation / Answer

Part A : The balanced reaction is : Na2O + H2O ----> 2NaOH

Molar mass (g/mol) 62 40

Part B :

Number of moles of Na2O is , n = mass/molar mass

= 2.85 g/(62(g/mol))

= 0.046 moles

1 mole of Na2O produces 2 moles of NaOH

0.046 moles of Na2O produces 2x0.046 = 0.092 moles of NaOH

Molarity of NaOH , M = number of moles / volume in L

= 0.092 moles / (250.0mL x ( 10-3 L/mL))

= 0.368 M

The Molarity of NaOH formed is 0.368 M

NaOH ---> Na+ + OH-

1 mole of NaOH produces 1 mole of OH-

[OH-] = [NaOH] = 0.368 M

pOH = - log[OH-] = - log0.368 = 0.43

pH = 14 - pOH = 14 - 0.43 = 13.57

Part D :

NaOH + HCl ---> NaCl + H2O

1 mole of NaOH reacts with 1 mole of HCl

0.092 moles of NaOH reacts with 0.092 moles of HCl

So volume of HCl required , V = number of moles / molarity

V = 0.092 moles / 0.0100 M

= 9.2 L

= 9200 mL of HCl

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