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Vadim26 [7]
3 years ago
5

Typical residential shower controls mix streams of hot water (140 F, or 60 C) with cold water (60 F, or 15 C) to form a stream o

f 40 C (104 F) water. The entire system loses energy to the surroundings at a rate of 5 kJ/kg of exiting water. What is the ratio of cold water-to-hot water mass flow rates necessary to provide the 40 C water?
Chemistry
1 answer:
sammy [17]3 years ago
3 0

Answer:

  4:5

Explanation:

Let x represent the fraction of the mix that is hot water. Then the temperature of the mix is ...

  60x +15(1-x) = 40·1

  45x = 25 . . . . . . . . . subtract 15

  x = 25/45 = 5/9 . . . divide by the coefficient of x

This is the fraction that is hot water, so the fraction that is cold water is ...

  1-5/9 = 4/9

The ratio of cold to hot is ...

  cold : hot = (4/9) : (5/9) = 4 : 5

_____

<em>Additional comments</em>

The problem assumes that the energy contained in a given mass of water is proportional to its temperature. That is almost true, sufficiently so that we can reasonably use that approximation.

If heat loss is figured into the problem, then additional information is needed regarding the energy content of water at temperatures in the range of interest. That is not provided by this problem statement, so we have ignored the heat loss.

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If m = 45g and V = 15ml, what is D in g/ml?​
ch4aika [34]

Answer:

3 g/mL

Explanation:

We know that the density of an object can be measured by dividing its mass (g) to its volume (mL).

Formula

D=m/v

Given data:

Mass= 45 g

Volume= 15 mL

Now we will put the values in formula:

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6 0
3 years ago
How many grams of CO are needed to react with an excess of Fe 2 O 3 to produce 209.7 g Fe?
gavmur [86]

Answer:

Mass = 157.5 g

Explanation:

Given data:

Mass of CO needed  = ?

Mass of Fe formed = 209.7 g

Solution:

Chemical equation:

3CO + F₂O₃   →       2Fe + 3CO₂

Number of moles of Fe:

Number of moles = mass/ molar mass

Number of moles = 209.7 g/ 55.85 g/mol

Number of moles = 3.75 mol

Now we will compare the moles of iron and carbon monoxide.

                               Fe            :              CO

                                 2            :              3

                                3.75         ;             3/2×3.75 = 5.625 mol

Mass of CO:

Mass = number of moles × molar mass

Mass = 5.625 mol × 28 g/mol

Mass = 157.5 g

4 0
3 years ago
A candle is 10 cm high and 2 cm in diameter physical or chemical property​
rewona [7]

Answer: Physical property

Explanation: length and dimensions are under physical properties of matter.

3 0
3 years ago
How do models help scientists predict the polarity of molecules?
yuradex [85]

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Explanation:

8 0
3 years ago
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Pls help, needed for chemistry
vovangra [49]

Answer:

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Explanation:

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