Question

When elemental sodium reacts with water, sodium hydroxide and hydrogen will form. What mass of sodium (in grams) must be reacted with excess water to produce 325 mL of hydrogen gas at 25.0oC and 1.15 atm?

Answer 1

Answer:

0.703g Na must reacted

Explanation:

The reaction of Sodium, Na, With water, H₂O is:

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

Where 2 moles of sodium reacts with an excess of water to produce 1 mole of hydrogen

To solve this question we have to use PV = nTR to solve the moles of the gas. With the moles of hydrogen we can find the moles of sodium that reacted and its mass:

Moles H₂:

PV = nRT

PV /RT = n

Where P is pressure = 1.15atm

V is volume in liters = 0.325L

R is gas constant = 0.082atmL/molK

T is absolute temperature = 25°C + 273 = 298.0K

1.15atm*0.325L / 0.082atmL/molK*298.0K = n

0.0153 moles of hydrogen are produced

Moles Na:

0.0153 moles H₂ * (2moles Na / 1mol H₂) = 0.0306 moles Na

Mass Na -Molar mass: 22.99g/mol-:

0.0306 moles Na * (22.99g / mol) =

0.703g Na must reacted