Chemistry, 25.07.2019 20:20, NatalieAllen11

Enter your answer in the provided box. pentaborane−9 (b5h9) is a colorless, highly reactive liquid that will burst into flames when exposed to oxygen. the reaction is 2b5h9(l) 12o2(g) → 5b2o3(s) 9h2o(l) calculate the kilojoules of heat released per gram of the compound reacted with oxygen. the standard enthalpy of formations of b5h9(l), b2o3(s), and h2o(l) are 73.2, −1271.94, and −285.83 kj/mol, respectively.

Answers: 1

Show answers

Answers

answered: savannahwonder

Answer : The heat released per gram of the compound reacted with oxygen is, 71.915 kJ

Solution :

The balanced chemical reaction is,

$2B_5H_9(l)+12O_2(g)\rightarrow 5B_2O_3(s)+9H_2O(l)$

The expression for enthalpy change is,

$\Delta H=\sum [n\times \Delta H_f(product)]-\sum [n\times \Delta H_f(reactant)]$

$\Delta H=[(n_{H_2O}\times \Delta H_{H_2O})+(n_{B_2O_3}\times \Delta H_{B_2O_3})]-[(n_{B_5H_9}\times \Delta H_{B_5H_9})+(n_{O_2}\times \Delta H_{O_2})]$

where,

n = number of moles

Now put all the given values in this expression, we get

$\Delta H=[(9\times -285.83)+(5\times -1271.94)]-[(2\times 73.2)+(12\times 0)]\\\\\Delta H=-9078.57kJ$

Now we have to calculate the heat released per gram of the compound reacted with oxygen.

As we know that,

1 mole of B_5H_9 has 63.12 grams of mass

So, 2 mole of B_5H_9 has $2\times 63.12=126.24$ grams of mass

As, 126.24 g of B_5H_9 release heat = 9078.57 kJ

So, 1 g of B_5H_9 release heat = $\frac{9078.57}{126.24}=71.915kJ$

Therefore, the heat released per gram of the compound reacted with oxygen is, 71.915 kJ

answered: Guest

to be fair, you have to have a very high iq to understand rick and morty. the humour is extremely subtle, and without a solid grasp of theoretical physics most of the jokes will go over a typical viewer's head. there's also rick's nihilistic outlook, which is deftly woven into his characterisation- his personal philosophy draws heavily from narodnaya volya literature, for instance. the fans understand this stuff; they have the intellectual capacity to truly appreciate the depths of these jokes, to realise that they're not just funny- they say something deep about life. as a consequence people who dislike rick & morty truly are idiots- of course they wouldn't appreciate, for instance, the humour in rick's existential catchphrase "wubba lubba dub dub," which itself is a cryptic reference to turgenev's russian epic fathers and sons. i'm smirking right now just imagining one of those addlepated simpletons scratching their heads in confusion as dan harmon's genius wit unfolds itself on their television screens. what fools.. how i pity them.

and yes, by the way, i do have a rick & morty tattoo. and no, you cannot see it. it's for the ladies' eyes only- and even then they have to demonstrate that they're within 5 iq points of my own (preferably lower) beforehand. nothin personnel kid