1 2 3 4 Compounds of boron and hydrogen arc remarkable for their unusual bonding
ID: 794301 • Letter: 1
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Compounds of boron and hydrogen arc remarkable for their unusual bonding and also for their reactivity. With the more reactive halogens, for example, diborane (B2H6) forms trihalides even at low temperatures: B2H6(g ) + 6 CI2(g) rightarrow 2 BC13(g) + 6 HCI(g ) Delta H rxn = -755.4 KJ How much heat is released when 3.763 kg of diborane reacts? (Give your answer in scientific notation.) A chemical engineer studying the properties of fuels placed 1.780 g of a hydrocarbon in the bomb of a calorimeter and filled it withO2 gas. The bomb was immersed in 2.550 L of water and the reaction initiated. The water temperature rose from20.00 degree C to 23.55 degree C. If the calorimeter (excluding the water) had a heat capacity of 403 J/K, what was the heat of reaction for combustion (q v) per gram of the fuel? (d for water = 1.00 g/mL; c for water = 4.184 J/g degree C.) Enter your answer in scientific notation. An unknown volume of water at 18.2 degree C is added to 31.8 mL of water at 35.0 degree C. If the final temperature is 23.5°C, what was the unknown volume? (Assume that no heat is lost to the surroundings; d of water is 1.00 g/mL.) One piece of copper jewelry at 125 degree C has exactly twice the mass of another piece, which is at 27 degree C. Both pieces are placed inside a calorimeter whose heat capacity is negligible. What is the final temperature inside the calorimeter of copper = 0.387 J/g mid dotK)?Explanation / Answer
A) Molecular weight of B2H6 = 27.5
Basis = 27.5 gms
Which is 1mole of B2H6
So when it reacts with 6moles of Cl2 Heat released is -755.4 KJ
27.5 gms of B2H6 reacts Delta H = - 755.4 KJ
when 3763 gms of B2H6 racts lets us assume "X" KJ of heat enrgy released
X = -755.4 * 3763 / 27.5
= -13366.189 KJ
Therefore heat released = 13366.189 Kilo Joules.
B) Density of water = 1 gm /ml
Volume of water = 2.550 lt
Mass of water = 1*2550 = 2550 gms
Heat of reaction is the negative sum of Heats released from water and bomb
qreaction = - (qwater + qbomb)
where qwater = 4.18 J/(g
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