Use the percent as mass in g
Mass g) --> g/mol
K, B and H molar mass from periodic table
54.93 g K x (1 mol K/ 39.10 g K) = 1.405 mol K
38.73 g B x (1 mol B/ 10.81 g B) = 3.583 mol B
6.34 g H x (1 mol H/ 1.008 g H) = 6.290 mol H
Divide all three answers by the smallest value and you will get
1.000 mol K
2.550 mol B
4.477 mol H
now multiply these three answers by a number that will make all a whole number or (a number with a 9 as the first decimal point)
so multiply by 2
2 mol k
5 mol B
and 9 mol H
E.F. = K2B5H9
Answer is D
Sorry for bad explanation!!!!!!
Answer:
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Explanation:
What caused agriculture to change in Britain leading to urbanization? Check all that apply.
Epsom salt is MgSO4.
We assume x water of hydration in the crystalline form.
Molecular mass of MgSO4 = 24+32+4*16=120
Molecular mass of MgSO4.xH2O = 120+18x
By proportion,
2.000/0.977 = (120+18x)/120
Cross multiply
0.977(120+18x) = 120*2.000
from which we solve for x
17.586x+117.24 = 240
x=122.78/17.586
=6.980
Answer: there are 7 water of hydration in Epsom salt, according to the experiment.
Note: more accurate (proper) results may be obtained by using exact values (3-4 significant figures) in the molecular masses. However, since water of hydration is the nearest integer, using approximate values (to at least two significant figures) suffice.
A). 4
.........................
1 mole --------------------------- 6.02 x 10²³ molecules
( moles lithium ) --------------- 1.2 x 10²¹ molecules
( moles lithium ) = (1.2 x 10²¹ ) x 1 / ( 6.02 x 10²³ )
= 1.2 x 10²¹ / 6.02 x 10²³
= 2.0 x 10⁻³ moles of lithium
Answer D
hope this helps!
