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atroni [7]
3 years ago
8

What is the total amount of heat released when 94.0 g water at 80.0 °C cools to form ice at −30.0 °C?

Chemistry
1 answer:
Wewaii [24]3 years ago
6 0

Answer:

The total amount of heat released  is  68.7 kJ

Explanation:

Given that:

mass of water = 94.0 g

moles of water = 94 / 18.02 = 5.216

80⁰C   ------>  0⁰C  -------->    -30⁰C

Q1 = m Cp dT

      = 94 x 4.184 x (0 - 80)

     = -31463.68 J

     = -31.43 kJ

Q2 = 6.01 x 10^3 x 5.216

    = - 31348.16 J

   = -31.35 kJ

Q3 = - 94 x 2.09 x 30

    = - 5893.8 J

   = -5.894 kJ

Total heat = Q1 + Q2 + Q3  = -31.43 kJ  + (-31.35 kJ  ) + (-5.894 kJ )  = -68.7 kJ

Total heat released = -68.7 kJ

Note that the "negative sign" simply indicates heat released, therefore no need to put it in the answer.

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When potassium carbonate and calcium chromate are mixed, which of the following will pass through a filter?
aliina [53]

Calcium carbonate will be formed which is insoluble in water.

The answer is a) K and CrO4 only.

8 0
3 years ago
Enter your answer in the provided box. an aqueous solution containing 10 g of an optically pure substance was diluted to 500 ml
sladkih [1.3K]

Answer:

[α] = -77.5° / \frac{\textup{dm-g}}{\textup{mL}}

Explanation:

Given;

Mass of optically pure substance in the solution = 10 g

Volume of water = 500 mL

Length of the polarimeter, l = 20 cm = 20 × 0.1 dm = 2 dm

measured rotation = - 3.10°

Now,

The specific rotation ( [α] ) is given as:

[α] = \frac{\alpha}{c\times l}

here,

α is the measured rotation = -3.10°

c is the concentration

or

c = \frac{\textup{Mass of optically pure substance in the solution}}{\textup{Volume of water}}

or

c =  \frac{10}{500}

or

c = 0.02 g/mL

on substituting the values, we get

[α] = \frac{-3.10^o}{0.02\times2}

or

[α] = -77.5° / \frac{\textup{dm-g}}{\textup{mL}}

7 0
3 years ago
How many moles of nitrogen are present at STP if the volume is 846L
Artyom0805 [142]
A mole of any gas occupied 22.4 L at STP. So, the number of moles of nitrogen gas at STP in 846 L would be 846/22.4 = 37.8 moles of nitrogen gas.

Alternatively, you can go the long route and use the ideal gas law to solve for the number of moles of nitrogen given STP conditions (273 K and 1.00 atm). From PV = nRT, we can get n = PV/RT. Plugging in our values, and using 0.08206 L•atm/K•mol as our gas constant, R, we get n = (1.00)(846)/(0.08206)(273) = 37.8 moles, which confirms our answer.
3 0
3 years ago
The arrows in the chart below represent phase transitions. Three bars are shown labeled Solid, Liquid, and Gas. They are connect
tester [92]

Answer:

1,2,3

Explanation:

Heat gain implies that heat is absorbed by the system in order to make the stated phase transition possible.

Before a liquid changes to gas, intermolecular forces in the liquid are broken by energy supplied as heat.

Also, transition from solid to liquid requires energy to break intermolecular bonds.

Finally, sublimation requires input of energy in the form of heat.

4 0
3 years ago
Read 2 more answers
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Rzqust [24]

Answer:

Explanation:

3Sn(NO3)2 (aq) +  2Cr(s) → 2Cr(NO3)3(aq ) + 3Sn(S )

5 0
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