A 250 ml flask contains He at a pressure of 700 torr and a temperature of 25 degrees c. What is the mass of He present?
Answers
Answer:
0.038 g He
Explanation:
From the question we are given;
Volume of the flask, V = 250 mL
Pressure of He, P = 700 torr
Temperature, T = 25°C, but K = 273 + °C
= 298 K
We are required to calculate the mass of Helium present in the flask.
We are going to use the ideal gas equation to first get the number of moles of He present in the flask.
Ideal gas equation, PV = nRT, where n is the number of moles and R is the ideal gas constant.
In this case, R will be 62.364 L.Torr/mol.K, since the pressure is in torr.
Rearranging the equation;
n = PV ÷ RT
= (0.25 L × 700 torr) ÷ (62.364 × 298 K)
= 0.00942 moles
With the number of moles, we can calculate the mass of He.
Mass = Number of moles × molar mass
Molar mass of He = 4.0 g/mol
Therefore,
Mass = 0.00942 moles × 4.0 g/mol
= 0.03768 g
= 0.038 g He
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Answers
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Halite
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the expression is in lowest terms, so you can’t do anything else
Answer:-64
Explanation:
Answers
#6).
Every 1,000 mL makes 1 L
How many 1,000mL are there in 2,800 mL ?
That's division.
(2,800 mL) / (1,000 mL) = 2.8 L
#7).
The 'perimeter' means the 'distance all the way around'.
You have to know that both sides of a rectangle are the same length,
and also the top and bottom are the same length.
So the perimeter of this rectangle is
(2 yd) + (4.5 yd) + (2.yd) + (4.5 yd) = 13 yd .
Oops. The problem wants to know the perimeter in feet.
So you have to know that each yard is the same as 3 feet.
In order to find the number of feet in 13 yards, you have to
take 3 feet 13 times .
(3 feet) times (13) = 39 feet .
#8).
For this one, you have to know that every 36 inches makes 1 yard.
How many 36 inches are there in 48 inches ?
That's division.
(48 inches) / (36inches) = 1 and 1/2 yards .
#9).
For this problem, you have to know how to handle a mixed number,
and you also have to know that there are 16 ounces in 1 pound.
Add up the fruit:
(3-1/2 pounds) + (4 pounds) + 2 pounds) = 9-1/2 pounds
Now, remember that each pound is the same as 16 ounces. So if you
want to find the number of ounces in 9-1/2 pounds, you have to take
16 ounces 9-1/2 times .
(16 ounces) times (9-1/2) = 152 ounces.
___________________________________
#10).
This one is just adding up some numbers. But after you finish doing that, you have to know that 1,000 meters is called '1 kilometer' .
Add up the distances that Omar ran:
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That's division.
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