Average atomic mass of an element is a sum of the product of the isotope mass and its relative abundance.
For example: Chlorine has 2 isotopes with the following abundances
Cl(35): Atomic mass = 34.9688 amu; Abundance = 75.78%
Cl(37): Atomic mass = 36.9659 amu; Abundance = 24.22 %
Average atomic mass of Cl = 34.9688(0.7578) + 36.9659(0.2422) =
= 26.4993 + 8.9531 = 35.4524 amu
Thus, the term “ average atomic mass “ is a <u>weighted</u> average so it is calculated differently from a normal average
½H2(g) + ½I2(g) → HI(g) ΔH = +6.2 kcal/mol
or...
½H2(g) + ½I2(g) + 6,2kcal/mole → HI(g)
________
21.0 kcal/mole + C(s) + 2S(s) → CS2(l)
or...
C(s) + 2S(s) → CS2(l) ΔH = +2,1 kcal/mole
_________
ΔH > 0 ----------->>> ENDOTHERMIC REACTIONS
Based on the information provided, it appears that you will need to calculate the amount of heat absorbed by the water from the peanut that was burned. We are given the following information:
specific heat capacity, c = 1.0 cal/g°C
mass of water = 76 g
Ti = 22°C
Tf = 46°C
change in temperature, ΔT = 24°C
We can use the formula q = mcΔT to measure the amount of energy absorbed by the water to increase in tempature:
q = (76 g)(1.0 cal/g°C)(24°C)
q = 1824 cal
Therefore, the water absorbed 1824 calories from the peanut that was burned.
Answer:
5 g
Explanation:
The heat required to vaporize ice is the sum of
i) Heat required to melt ice at 0°C
ii) Heat required to raise the temperature from 0°C to 100°C
iii) Heat required to vaporize water at 100°C
Thus;
H = nLfus + ncθ + nLvap
H= n(Lfus + cθ + Lvap)
Lfus = 6.01 kJ/mol
Lvap = 41 kJ/mol
c = 75.38
n =?
2100 = n(6.01 + 75.38(100) + 41)
n = 2100 KJ/7585.01 kJ/mol
n = 0.277 moles
Mass of water = number of moles * molar mass
Mass of water = 0.277 moles * 18 g/mol
Mass of water = 5 g
Answer:
Mass, m = 1.51 grams
Explanation:
It is given that,
The circumference of Aluminium cylinder, C = 13 mm = 1.3 cm
Length of the cylinder, h = 4.2 cm
We know that the density of the Aluminium is 2.7 g/cm³
Circumference, C = 2πr
Density is equal to mass per unit volume.
m is mass of the cylinder
V is the volume of the cylinder
So,
So, the mass of the cylinder is 1.51 grams.
