The temperature difference between the inside and the outside of a house on a cold winter day is 33°F. (a) Express this differen
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Answer:
<em>There must be added 500 cm3 of alcohol to bring the concentration to 80%.</em>
Explanation:
<u>Concentration</u>
The concentration of a solution is a measure of the amount of solute that has been dissolved in a given amount of solution.
In the container, there are 2 liters (2000 cubic centimeters) of a solution, 75% of which is alcohol (solute) and 25% of water (solvent).
The original amount of alcohol is:
H = 2000*75% = 1500 cc
The original amount of water is:
W = 2000*25% = 500 cc
When we add x cc of pure alcohol, there are 1500+x cc of alcohol out of 2000+x cc of solution.
The new concentration is calculated as:
And it's known this concentration is 80% (0.8), thus:
Multiplying by 2000+x:
Operating:
Rearranging:
x= 500
There must be added 500 cm3 of alcohol to bring the concentration to 80%
Answer:
<em>2 m/s</em>
<em></em>
Explanation:
The electromagnetic flow-metre work on the principle of electromagnetic induction. The induced voltage is given as
where is the induced voltage = 2.88 mV = 2.88 x 10^-3 V
is the distance between the electrodes in this field which is equivalent to the diameter of the tube = 1.2 cm = 1.2 x 10^-2 m
is the velocity of the fluid through the field = ?
is the magnetic field = 0.120 T
substituting, we have
2.88 x 10^-3 = 0.120 x 1.2 x 10^-2 x
2.88 x 10^-3 = 1.44 x 10^-3 x
= 2.88/1.44 = <em>2 m/s</em>