Answer:
4.8 g H₂O
Explanation:
To find the mass of water, you need to (1) convert grams B₂H₆ to moles B₂H₆ (via molar mass from periodic table), then (2) convert moles B₂H₆ to moles H₂O (via mole-to-mole ratio from reaction coefficients), and then (3) convert moles H₂O to grams H₂O (via molar mass from periodic table).
It is important to arrange the ratios/conversions in a way that allows for the cancellation of units (the desired unit should be in the numerator). The final answer should have 2 sig figs because the given value (3.7 grams) has 2 sig figs.
Molar Mass (B₂H₆): 2(10.811 g/mol) + 6(1.008 g/mol)
Molar Mass (B₂H₆): 27.67 g/mol
1 B₂H₆ + 3 O₂ ---> 2 HBO₂ + 2 H₂O
^ ^
Molar Mass (H₂O): 15.998 g/mol + 2(1.008 g/mol)
Molar Mass (H₂O): 18.014 g/mol
3.7 g B₂H₆ 1 mole 2 moles H₂O 18.014 g
---------------- x --------------- x ----------------------- x ----------------- = 4.8 g H₂O
27.67 g 1 mole B₂H₆ 1 mole
a. 43.1 g
b. 38.2%
<h3>Further explanation</h3>
Given
32.5 grams of NaOH
Required
The theoretical yield of Na₂CO₃
The percent yield
Solution
Reaction
2NaOH(s) + CO₂(g) → Na₂CO₃(s) + H₂O(l)
mol NaOH :
= mass : MW
= 32.5 : 40 g/mol
= 0.8125
mol Na₂CO₃ from the equation :
= 1/2 x mol NaOH
= 1/2 x 0.8125
= 0.40625
a.
Mass Na₂CO₃ :
= mol x MW Na₂CO₃
= 0.40625 x 106 g/mol
= 43.0625≈43.1 g
b. % yield = (actual/theoretical) x 100%
%yield = 16.45/43.1 x 1005
%yield = 38.17%≈38.2%
It represents
<h2>A) 1,000 grams</h2>
(1 kilogram = 1000 grams)
125 Kelvin turns into -146 C
