Quiz due today never understood this so can someone please help :)

Pentaborane-9, B5H9, is a colorless, highly reactive liquid that will burst into flame when exposed to oxygen. The reaction is 2

mina [271]

Answer: The amount of energy released per gram of $B_5H_9$ is -71.92 kJ

Explanation:

For the given chemical reaction:

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

The equation used to calculate enthalpy change is of a reaction is:

$\Delta H^o_{rxn}=\sum [n\times \Delta H^o_f_{(product)}]-\sum [n\times \Delta H^o_f_{(reactant)}]$

The equation for the enthalpy change of the above reaction is:

$\Delta H^o_{rxn}=[(5\times \Delta H^o_f_{(B_2O_3(s))})+(9\times \Delta H^o_f_{(H_2O(l))})]-[(2\times \Delta H^o_f_{(B_5H_9(l))})+(12\times \Delta H^o_f_{(O_2(g))})]$

Taking the standard enthalpy of formation:

$\Delta H^o_f_{(B_2O_3(s))}=-1271.94kJ/mol\\\Delta H^o_f_{(H_2O(l))}=-285.83kJ/mol\\\Delta H^o_f_{(B_5H_9(l))}=73.2kJ/mol\\\Delta H^o_f_{(O_2(g))}=0kJ/mol$

Putting values in above equation, we get:

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

We know that:

Molar mass of pentaborane -9 = 63.12 g/mol

By Stoichiometry of the reaction:

If 2 moles of $B_5H_9$ produces -9078.57 kJ of energy.

Or,

If $(2\times 63.12)g$ of $B_5H_9$ produces -9078.57 kJ of energy

Then, 1 gram of $B_5H_9$ will produce = $\frac{-9078.57kJ}{(2\times 63.12)}\times 1g=-71.92kJ$ of energy.

Hence, the amount of energy released per gram of $B_5H_9$ is -71.92 kJ

8 0

3 years ago

Help with science----?????///

N76 [4]

Answer + Explanation:

1. The different ways tectonic plates move in relation to each other are:

convergent (where plates move into one another)

divergent (where plates move apart)

transform (where plates move sideways in relation to each other)

2. Convergent plate boundaries can result in:

earthquakes, volcanoes, and the formation of mountains.

The Himalaya Mountains are the result of convergent plate boundaries.

3. Landforms that are a result of divergent boundaries are rift valleys and mid-oceanic ridges.

Locations where this occurs are: Mid-Atlantic Ridge, Red Sea Rift, Baikal Rift Zone

, East African Rift, East Pacific Rise, Gakkel Ridge, Galapagos Rise, and Explorer Ridge.

4. Transforming plate boundaries results in shallow earthquakes, large lateral displacement of rock, and a broad zone of crustal deformation.

A location where this occurs is: San Andreas Fault in western California

sorry that's all I can help you with today :/ if I have more time I'll answer the other questions!! If I helped you please don't forget to mark me brainliest!!

- sophi

8 0

2 years ago

Which of these elements does not exist as a diatomic molecule? (1 point)?

Over [174]

What are the elements so i can help?????

5 0

3 years ago

Read 2 more answers

The representative particle for KBr is the?

Flauer [41]

Answer: