Answer:
True
Explanation:
Stars are bright and enormous astronomical bodies that are located at a large distance from the earth. They are made up of the lightest gaseous elements namely hydrogen and helium. These hydrogen atoms undergo the reaction of nuclear fusion, which fuels the energy of the star and allows the star to shine, releasing a large amount of energy. They are located about trillions of miles away from the location of the earth, due to which they appear smaller in size.
Thus, the above-given statement is True.
Answer:
When objects collide, energy can be transferred from one object to another, thereby changing their motion. Energy can also be transferred from place to place by electric currents, which can then be used locally to produce motion, sound, heat, or light.
The heat of the reaction, in kJ, when 4.18 g of the hydrocarbon are combusted 775.70 kJ.
The heat energy is given as :
q = m c ΔT + Ccal ΔT
q = ( 974 g× 4.184 ×6.9) + 624 ×6.9
q = 32424.59 J
moles of hydrocarbon = 0.0418 mol
heat of combustion = 32424.59 J / 0.0418 mol
= 775707.89 J
= 775.70 kJ
Thus, A 4.18 g sample of a hydrocarbon is combusted in a bomb calorimeter that contains 974 g of water. the temperature of the water increases by 6.9 °C when the hydrocarbon is combusted. the calorimeter constant for the calorimeter was determined to be 624 J/°C. what is the heat of the reaction is 775.70 kJ.
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Reaction equation:
K₂CrO₄(aq) + PbCl₂(aq) → 2KCl(aq) + PbCrO₄(s)
Concentration = moles / Liter
moles(K₂CrO₄) = 3 x 0.025
= 0.075
By the equation, we see that the molar ratio of
K₂CrO₄ : PbCrO₄ is
1 : 1
moles(PbCrO₄) = 0.075
mass = moles x Mr
mass = 0.075 x (207 + 52 + 16 x 4)
mass = 24.2 grams
