A student determining the percent by mass of water in a hydrated crystal obtained the following data.
Mass of crystal before heating....5.0 g
Mass of crystal after 1st heating..4.0 g
Mass of crystal after 2nd heating..4.0 g
What is the percent by mass of water in the hydrate?
a- 0.80%
b- 0.20%
c- 20.%
d- 80.%
thanks in advance =)
2007-12-30 13:06:34 · 3 answers · asked by person 3 in Science & Mathematics ➔ Chemistry
The mass of the crystal dropped by 1.0g after 2 heatings. That means 1.0g of water turned into gas. Thus, the % of mass of water in the hydrate is
1.0/5.0g = 0.2*100% = 20%
[Answer: C]
2007-12-30 13:10:00 · answer #1 · answered by ¿ /\/ 馬 ? 7 · 0⤊ 0⤋
(1-4/5 ) x 100 = 20%
2007-12-30 13:12:51 · answer #2 · answered by + cruz + 2 · 0⤊ 0⤋
Mass loss due to heating is 1gram. % mass loss due to heating is 1/5 x 100 = 20%. You need to assume that the total mass loss is due to water being evaporated.
Your answewr should be (c)
2007-12-30 13:12:51 · answer #3 · answered by buncer1 2 · 0⤊ 0⤋