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neonofarm [45]
3 years ago
13

Which factors cause earth to experience seasons? Check all that apply.

Chemistry
2 answers:
Nataly [62]3 years ago
4 0

Answer:

the speed of the earth's rotation, the tilt of the earth's axis and the directness of the sun

Ainat [17]3 years ago
3 0

Answer:

B, C

Explanation:

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What is the oxidation state of Fe(s)
ad-work [718]

The  oxidation state is zero for Fe (s)

8 0
3 years ago
Culinary arts HELP FAST 1. Most people don't often think about science and restaurants or the food industry as
Andrews [41]

Answer:

i dont know

Explanation:

6 0
3 years ago
1.what happens in the nucleus of an atom when an alpha particle is emitted?
coldgirl [10]
1) The nucleus of an atom loses 2 protons and 4 neutrons.
2) The nucleus of an atom gains a proton and it's neutrons remain the same.
7 0
3 years ago
Read 2 more answers
The vapor pressure of water at 25.0°c is 23.8 torr. determine the mass of glucose (molar mass = 180 g/mol) needed to add to 500.
svp [43]
Q: A
according to this formula, we can get the mole fraction of water (n):
P(solu) = n Pv(water)
when we have Pv(solu) = 22.8 and Pv(water) = 23.8 so by substitution:
22.8 = n * 23.8
n= 0.958
- we need to get the moles of glucose:
moles of water = 500 g(mass weight) / 18 (molar weight)= 27.7 mol
n = moles of water / ( moles of water + moles of glucose)
0.958   = 27.7 / ( 27.7+ moles of glucose)
0.958 moles of glucose + 26.5 = 27.7
0.968 moles of glucose = 1.2
moles of glucose = 1.253 mol
∴ the mass of glucose = no.of glucose moles x molar mass 
                                      = 1.253 x 180 = 225.5 g
Q: B
here we also need to get n (mole fraction of water )by using this formula:
Pv(solu) = n Pv(water)
when we have Pv(solu)=132 & Pv(water)=150 so, by substition:
132= n * 150
n = 0.88
so, mole fraction of solution = 1 - 0.88 = 0.12
and we can get after that the moles of water = (mass weight / molar mass)
- no.moles of water = 85 g / 18 g/mol = 4.7 moles
- total moles in solution = moles of water / moles fraction of water 
                                        = 4.7 / 0.88 = 5.34 moles 
∴ moles of the solution = total moles in solu - moles of water 
                                       = 5.34 - 4.7 = 0.64 moles solute
∴ the molar mass of the solute = mass weight of solute / no.of moles of solute
                                                    = 53.8 / 0.64 = 84 g/mole

Q: C

moles of urea (NH2)2 CO = mass weight / molar mass
                                           = 4.49 g / 60 g /mol
                                           = 0.07 mol
moles of methanol = mass weight / molar mass 
                                 = 39.9  g / 32  g/mol = 1.25 mol
moles fraction of methanol = moles of methanol / (moles of methanol + moles of urea )
moles fraction of methanol = 1.25 / ( 1.25+0.07) = 0.95
by substitution in Pv formula we will be able to get the vapour pressure of the solu :
Pv(solu) = n P°v
Pv(solu) = 0.95 * 89 mm Hg 
∴Pv(solu) = 84.55 mmHg


 
7 0
3 years ago
A scientist measures the standard enthalpy change for the following reaction to be 67.9 kJ:
bekas [8.4K]

Answer: The standard enthalpy of formation  of H_2O(g) is  -252.1 kJ/mol.

Explanation:

The balanced chemical reaction is,

Fe_2O_3(s)+3H_2(g)\rightarrow 2Fe(s)+3H_2O(g)

The expression for enthalpy change is,

\Delta H=[n\times H_f_{products}]-[n\times H_f_{reactantss}]

Putting the values we get :

\Delta H=[2\times H_f{Fe}+3\times H_f{H_2O}]-[1\times H_f{Fe_2O_3}+3\times H_f{H_2}]

67.9kJ=[(2\times 0)+(3\times H_f{H_2O})]-[(1\times -824.2kJ/mol)+3\times 0kJ/mol)]

H_f{H_2O}=-252.1kJ/mol

Thus standard enthalpy of formation  of H_2O(g) is  -252.1 kJ/mol.

3 0
3 years ago
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