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ch4aika [34]
3 years ago
15

Sooo i suck at science like a lot . even tho i have a 70....can someone help me pls?

Chemistry
1 answer:
AleksAgata [21]3 years ago
7 0

Answer:

it is A

Explanation: the only way to possibly know that is if they are in the same level or if the dinosaur bones were found above the level of trilobites

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In a reaction vessel, 17.6 g of solid chromium(III) oxide, Cr2O3, was allowed to react with excess carbon tetrachloride in the f
notsponge [240]

Answer:

72.53% is the yield of CrCl3

Explanation:

Given

Reaction:

Cr2O3(s) + 3 CCl4(l) → 2 CrCl3(s) + 3 COCl2(aq)

CCl4 is in excess and 17.6g  Cr2O3 present

The reaction yields 26.6g of CrCl3

To Find:

% yields of the reaction

Also given

Molar mass of CrCl3 = 158.35g/mol

Molar mass of Cr2O3 = 152.00 g/mol

By the stoichiometry of the reaction

1 mole of Cr2O3 gives  2 moles of CrCl3

0r

1 x1 52 g of Cr2O3 gives 2x 158.35 g of CrCl3

= 1 52 g of Cr2O3 gives 316.70 g of CrCl3

    17.6 g of Cr2O3 gives  (17.6÷152) × 316.70 g CrCl3

= 36.67 g CrCl3

but actual yield is only 26.6g

so % yield is (26.6 ÷÷ 36.67) × 100

= 72.53% is the yield of CrCl3

8 0
3 years ago
HELP!! Please answer!
zloy xaker [14]

Answer: the % is 99.73 and the mass is 40.986

Explanation:

5 0
3 years ago
Katie looks out her bedroom window on a clear night. The stars in the sky look like tiny points of light.
jok3333 [9.3K]

Answer:

The Sun looks bigger than other stars because its more closer to the earth than the stars.the farther anything is distant from us the tinier it will look

Explanation:

plz mark brainliest if thats ok|?

6 0
2 years ago
Read 2 more answers
The change in internal energy for the combustion of 1.0 molmol of octane at a pressure of 1.0 atmatm is -5084.1 kJkJ . Part A If
Dovator [93]

Answer:

W = -10.3 kJ

Explanation:

During combustion, the system performs work and releases heat. Therefore, the change in internal energy is negative, and the change in enthalpy, which is equal to heat at constant pressure, is also negative. Work is then calculated by rearranging the equation for the change in internal energy:

w=ΔE−qp=−5084.3 kJ−(−5074.0 kJ)

The release of heat is much greater than the work performed by the system on its surroundings. The potential energy stored in the bonds of octane explains why considerably large amounts of energy can be lost by the system during combustion.

3 0
2 years ago
A sample of nitrogen gas expands in volume from 1.3 to 5.7 L at constant temperature. Calculate the work done in joules if the g
just olya [345]

Answer:

a) 0 J

b)  -2.67x10² J

c) -2.09x10³ J

Explanation:

For an isothermic expansion (with constant temperature) the work (W) is :

W = -pΔV, where p is the pressure and ΔV the volume variation. The minus signal is used because the compression is positive and ΔV is negative (Vf < Vi).

a) In vacuum, the relative pressure is 0 atm, so the work:

W = -0x(5.7 - 1.3)

W = 0 J

b) For a constant pressure of 0.60 atm

W = -0.6atmx(5.7 - 1.3)L = -2.64 L.atm

1 L.atm = 101.3 J

W = -2.64x101.3 = -2.67x10² J

c) For a pressure of 4.7 atm

W = -4.7atmx(5.7 - 1.3) L = - 20.68 atm.L

1 atm.L = 101.3 J

W = -20.68x101.3 = -2.09x10³ J

7 0
3 years ago
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