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4 years ago

By using the following reactions, calculate the heat of combustion of pentane:

1 answer:

6 0

To answer this problem, we use Hess' Law to calculate the overall enthalpy of the reactions. The goal is to add all the reactions such that the final reaction is C<span>5H12 (g) + 8O2 (g) → 5CO2 (g) + 6H2O (l) through cancellation adn multiplication. The first equation is multiplied by 5, the second one is multiplied by 6 and the third one is reversed. The final answer is -3538 J or -3.54 x10^3 kJ.</span>

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Explain why Statutes coated with white lead on long exposure to atmosphere

g100num [7]

Answer:

Its because once you go black, there's no going back

Explanation:

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3 years ago

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A 51.24-g sample of Ba(OH)2 is dissolved in enough water to make 1.20 liters of solution. How many mL of this solution must be d

g100num [7]

Answer:

0.40 L

Explanation:

Calculation of the moles of $Ba(OH)_2$ as:-

Mass = 51.24 g

Molar mass of $Ba(OH)_2$ = 171.34 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{51.24\ g}{171.34\ g/mol}$

$Moles= 0.2991\ mol$

Volume = 1.20 L

The expression for the molarity is:

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

$Molarity=\frac{0.2991\ mol}{1.20\ L}=0.24925\ M$

Thus,

Considering

$Molarity_{working\ solution}\times Volume_{working\ solution}=Molarity_{stock\ solution}\times Volume_{stock\ solution}$

Given that:

$Molarity_{working\ solution}=0.100\ M$

$Volume_{working\ solution}=1\ L$

$Volume_{stock\ solution}=?$

$Molarity_{stock\ solution}=0.24925\ M$

So,

$0.100\ M\times 1\ L=0.24925\ M\times Volume_{stock\ solution}$

$Volume_{stock\ solution}=\frac{0.100\times 1}{0.24925}\ L=0.40\ L$

<u>The volume of 0.24925M stock solution added = 0.40 L </u>

6 0

3 years ago

How many moles of potassium are contained in 449 g of potassium?.

stira [4]

Answer:

12.8 moles of potassium

Explanation:

449 g/39.10 g = 12.76 moles

First, you divide 449 g of potassium by its molar mass which is 39.10 g. Then you will get your answer, but you need to round it to 3 numbers because of Sig Figs, which makes it 12.8 moles.

7 0

2 years ago

which idea did john dalton include in his atomic theory? a. all atoms are the same size. b. atoms of the same element are identi

lapo4ka [179]

It might be c, because he came up with the plum pudding model. or it might be that atoms of the same element are identical, but that's not true cuz ions are different and isotopes are different.

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4 years ago

Write a balanced chemical equation for the reaction of solid potassium with liquid water. express your answer as a chemical equa

murzikaleks [220]

In writing chemical reactions, it is important that you know the chemical formula of each substance and in balancing them, it should be that the number of each element in both side are equal.

2K(s) + 2H2O(l) = 2KOH(aq) + H2(g)

4 0

3 years ago

Read 2 more answers