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HACTEHA [7]
3 years ago
7

When a substance burns, a chemical reaction is taking place. True False

Chemistry
2 answers:
zvonat [6]3 years ago
4 0

Answer:

True

Explanation:

Hitman42 [59]3 years ago
3 0

true

hope this helped bud :)

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Use the diagram below to answer the question.
oksian1 [2.3K]

Answer: Every action force results in an equal and opposite reaction force.

Explanation: newtons law

5 0
3 years ago
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What is the approximate mass of one mole of zinc?
VikaD [51]
The answer is (a) 30g. Zinc = 30. 1 mole = 30 x 1 = 30g
6 0
3 years ago
How many grams of Ni are formed from 55.3 g of Ni2O3?<br><br> 2Ni2O3(s)⟶4Ni(s)+3O2(g)
Neko [114]

Answer:

39.2 g

Explanation:

  • 2Ni₂O₃(s) ⟶ 4Ni(s) + 3O₂(g)

First we <u>convert 55.3 grams of Ni₂O₃ into moles of Ni₂O₃</u>, using its<em> molar mass</em>:

  • 55.3 g ÷ 165.39 g/mol = 0.334 mol Ni₂O₃

Then we <u>convert 0.334 moles of Ni₂O₃ into moles of Ni</u>, using the <em>stoichiometric coefficients of the balanced reaction</em>:

  • 0.334 mol Ni₂O₃ * \frac{4molNi}{2molNi_2O_3} = 0.668 mol Ni

Finally we <u>calculate how much do 0.668 Ni moles weigh</u>, using the<em> molar mass of Ni </em>:

  • 0.668 mol Ni * 58.69 g/mol = 39.2 g
7 0
3 years ago
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
Which of the following statements is true?
liubo4ka [24]

Answer:

a is the anwser

Explanation:

4 0
3 years ago
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