g chem and math quest

[xoangelxo]

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1) 39g of calcium flouride contains
a) one-half mole of flouide ions
b)Two moles of calcium ions
c) One mole of calcium ions
d) One mole of fluoride ions
e) Two moles of fluoride ions

2) If the angles of a triangle are in the ratio of 2:3:7 then the degree measures of the angles must be? (ANS: 30-45-105)

Whats an easy way to do this..it seems easy, but im drawing a blank?! Thanks.

 

[Dotoday]

Ok, soo, 2:3:7 and the angles are 30:45:105.
Well look at the ratios:

3/2 = 1.5 and 45/30 = 1.5
7/3 = 2.3 and 105/45 = 2.3
7/2 = 3.5 and 105/30 = 3.5

There you go 2:3:7 ratio is the same as 30:45:105.
That was an easy problem.

 

[domonas]

1) 39g of calcium flouride contains
a) one-half mole of flouide ions
b)Two moles of calcium ions
c) One mole of calcium ions
d) One mole of fluoride ions
e) Two moles of fluoride ions

2) If the angles of a triangle are in the ratio of 2:3:7 then the degree measures of the angles must be? (ANS: 30-45-105)

Whats an easy way to do this..it seems easy, but im drawing a blank?! Thanks.

1. Calcium Fluoride has a molecular weight of 78g/mol
39g of caf2 is 1/2 mol or C(1/2)F(1)
thus, the answer is D (I think)

2. the way i would answer this is 2+3+7 = 12
180/12 = 15
2x15=30
3x15=45
7x15=105

 

[DrillFillSeal]

Where did you find your questions? Just curious. Thanks.

 

[xoangelxo]

the math one is from topscore practice test 2, and the gchem one is actually in the tutorial on the ada website, lol

 

[artsyme]

1) 39g of calcium flouride contains
a) one-half mole of flouide ions
b)Two moles of calcium ions
c) One mole of calcium ions
d) One mole of fluoride ions
e) Two moles of fluoride ions

2) If the angles of a triangle are in the ratio of 2:3:7 then the degree measures of the angles must be? (ANS: 30-45-105)

Whats an easy way to do this..it seems easy, but im drawing a blank?! Thanks.

1) D
Calcium Flouride is CaF2......which means the following are equal:
1* mole of CaF2 , 1* mole of Ca, 2* moles of F (CaF2 --> Ca + 2F )

39 grams of CaF2 = .5 moles of CaF2
Therefore. there are .5x1* moles of CaF2, .5x1* moles of Ca, and .5x2* moles of F.

2) There are 180 degrees in a triangle and the ratio is 2:3:7 so:
2x + 3x + 7x = 180
12x = 180
x = 15*
2(15*) = 30, 3(15*) = 45, 7(15*) = 105

Hope this helps!