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3 years ago

What qualities make one theory "better" than another in the scientific community?

1 answer:

5 0

Some theories may have better reasoning than others. Sometimes, it even depends on who made the theory. If a highly respected scientist made a theory, his or hers may be looked at as better than others,

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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

Which of the following is NOT a factor that determines how much energy we need?

german

Answer:

B) The amount of vitamin D gained in 1 day.

Explanation:

6 0

2 years ago

Read 2 more answers

Calculate the specific heat of a piece of wood if 2000 g of wood absorbs 75,250 J of heat, and its temperature changes from 30°C

inna [77]

Answer:

Explanation:

The specific heat capacity=quantity of heat in joule/mass×change in temperature

from this question the quantity of heat is 75250,the mass is 2000 and the change in temperature is 50-30

which is 20

therefore

c=75250/2000×20

c=75250/40000

c=1.88

I hope this helps

3 0

3 years ago

HELP WHOEVER ANSWERS WILL BE MARKED BRAINLIEST

Vika [28.1K]

1) T
2) F- the heart pumps blood
3) T
4) F- atria and ventricles
5) T
6) T
7) T
8) T
9) F- your heart rate goes down but doesn't stop
10) T

1) D
2) B
3) A
4) E
5)C

7 0

2 years ago

At equilibrium, Keq for the following reaction is equal to 3.5: SO2 + NO20 È SO3 + NO a) Is a beaker containing 2.5 M SO2, 2.0 M

liraira [26]

Keq=[SO3][SO2] /[SO2][NO2]

4 0

3 years ago