Answer:
per mole of pentane = 3157.53 kJ/mol
Explanation:
Given:
Mass of pentane, m = 0.468 gram
Molar mass of pentane, M = 72.15
Now, mol of pentane, n = mass/M = 0.468/72.15 = 0.00648 mol of C5H12
Now,
ΔT = 23.65 - 20.45 = 3.2°C
Heat capacity of the calorimeter, C = 2.21 kJ/°C
Specific heat capacity of the water, Cp = 4.184 J/g.°C
Now,
the heat gained = the heat lost
also,
or
and
Now,
we have,
(Here negative sign depicts the release of the heat)
per mole of pentane =-20460.8/(0.00648 ) = 3157.53 kJ/mol
Exercise 8. Compare the meanings of these verbs.
Came out - came, left - came, brought - drove, looked -
looked, drove - drove away, said - told.
Answer:
39 square feet
Explanation:
The formula for figuring out the area of a triangle is base x height x 0.5 therefore each triangles area is 7.5 square feet x 4 which is 30 and the base of the pyramids area is equal to 9 square feet. 30 plus 9 equals 39 square feet.
Answer:
80 cm.
Explanation:
Since the metre rule is 1 m i.e 100 cm it means that the mass of the metre can be obtained at the 50 cm mark.
But the metre is pivoted at the 60 cm.
Please refer to the attached photo for details.
In the attached photo, y is the distance between the mark (that will balance the metre rule when a 50 g mass is hunged) and the pivot.
Thus, we can obtain the value of y as follow:
Anticlock wise moment = Clock wise moment
Anticlock wise moment = 100 × 10
Clock wise moment = y × 50
Anticlock wise moment = Clock wise moment
100 × 10 = y × 50
Divide both side by 50
y = (100 × 10) /50
y = 20 cm
Now, to obtain the mark, B that will balance the metre, we simply add 20 cm to 60 cm ie
B = 60 + 20
B = 80 cm
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