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devlian [24]
10 months ago
8

Please help don’t understand this I attached the question

Chemistry
2 answers:
Rasek [7]10 months ago
8 0

Answer:

58.32

Explanation:

The mass number is one mole and for Mg it is 24.306 for O it is 15.999 and for H it is 1.008. because O and H have 2, you multiply them by 2 and add all the numbers and it equals 58.32

Eva8 [605]10 months ago
7 0
When you take the molar mass of the elements and add them all together you get 58.32g/mol

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A bomb calorimetric experiment was run to determine the enthalpy of combustion of ethanol. The reaction is The bomb had a heat c
gulaghasi [49]

Answer:

The enthalpy of combustion of ethanol in kJ/mol is -1419.58  kJ/mol.

Explanation:

The heat absorbed by the bomb and water is equal to the product of the heat  capacity and the temperature change. Working with this equation, and assuming no heat is lost to  the surroundings, we write :

qcal= Ccal × ΔT= 490 J/K × 276.7 K= <u>135,583 J</u> = 135.58 kJ

Note we expressed the temperature change in K, because the heat capacity is written in K.

<u> Now that we have the heat of combustion, we need to calculate the molar heat.  </u>

Because qsystem = qrxn + qcal and qrxn = -qcal, the heat change of the reaction is -135.58 kJ.

This is the heat released by the combustion of 4.40 g of ethanol ; therefore, we can write  the <u>conversion factor as 135.58 kJ/ 4.40 g</u>.

The molar mass of ethanol is 46.07 g, so the heat of combustion of 1 mole of ethanol is :

molar heat of combustion= -135.58 kJ/4.40 g x 46.07 g/ 1 mol= -1419.58 kJ/mol

Therefore, the enthalpy of combustion of ethanol in kJ/mol is -1419.58  kJ/mol.

3 0
3 years ago
Complete the statement to describe the calcium concentration that must be maintained in human body cells. ( fill in the blank )T
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Answer:

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Explanation:

My previous answer was deleted from the explanation I provided from another website.

7 0
3 years ago
Read 2 more answers
2. This graph shows the energy involved in a reaction involving two molecules. Describe what is happening or what the state of t
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If you think of it endothermic is when there is energy needed for the reaction to occur and exothermic is when the reaction releases energy
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3 years ago
An archaeologist graduate student found a leg bone of a large animal during the building of a new science building. The bone had
Vlad [161]

Answer : The time passed in years is 2.74\times 10^2\text{ years}

Explanation :

Half-life of carbon-14 = 5730 years

First we have to calculate the rate constant, we use the formula :

k=\frac{0.693}{t_{1/2}}

k=\frac{0.693}{5730\text{ years}}

k=1.21\times 10^{-4}\text{ years}^{-1}

Now we have to calculate the time passed.

Expression for rate law for first order kinetics is given by:

t=\frac{2.303}{k}\log\frac{a}{a-x}

where,

k = rate constant  = 1.21\times 10^{-4}\text{ years}^{-1}

t = time passed by the sample  = ?

a = initial amount of the reactant disintegrate = 15.3

a - x = amount left after decay process = 14.8

Now put all the given values in above equation, we get

t=\frac{2.303}{1.21\times 10^{-4}}\log\frac{15.3}{14.8}

t=274.64\text{ years}=2.74\times 10^2\text{ years}

Therefore, the time passed in years is 2.74\times 10^2\text{ years}

4 0
3 years ago
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