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2 years ago

What is the thermal energy needed to completely melt 9.60 mol of ice at 0.0 C

Chemistry

2 answers:

jeka57 [31]2 years ago

5 0

Answer:

57.792 kJ

Explanation:

Molar enthalpy of fusion of the substance is defined as the energy required to convert the substance in solid state, at its melting point to liquid state at constant pressure and no change in temperature.

For example the energy required to convert 1 mole of water (ice) at 0°C to 1 mole of water (liquid) at 0°C is 6.02 kJ/mol.

Thus, thermal energy required to convert 9.60 moles of ice is 6.02×9.60 kJ = 57.792 kJ

inysia [295]2 years ago

4 0

The thermal energy needed to completely melt 9.60 mole of ice at 0.0 C is 57.8 Kj

Explanation
ice melt to form water

The molar heat of fusion for water is 6.02 Kj/mol
Thermal energy = moles x molar heat of fussion for water

=9.6 mol x6.02 kj/mol =57.8 Kj

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At 73.0 ∘c , what is the maximum value of the reaction quotient, q, needed to produce a non-negative e value for the reaction so

damaskus [11]

Here we will use the general formula of Nernst equation:

Ecell = E°Cell - [(RT/nF)] *㏑Q

when E cell is cell potential at non - standard state conditions

E°Cell is standard state cell potential = - 0.87 V

and R is a constant = 8.314 J/mol K

and T is the temperature in Kelvin = 73 + 273 = 346 K

and F is Faraday's constant = 96485 C/mole

and n is the number of moles of electron transferred in the reaction=2

and Q is the reaction quotient for the reaction
SO42-2(aq) + 4H+(aq) +2Br-(aq) ↔ Br2(aq) + SO2(g) +2H2O(l)

so by substitution :

0 = -0.87 - [(8.314*346K)/(2* 96485)*㏑Q → solve for Q

∴ Q = 4.5 x 10^-26

6 0

2 years ago

Which changes occur when Pt2+ is reduced?

skad [1K]

The correct answer is option 2. When Pt2+ is reduced it loses electrons, oxidizing it. The oxidation number is the charge of the atom. Adding an electron, decreases the net charge consequently the oxidation number.

3 0

2 years ago

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The specific heat of water is 4.18 J/g•°C. How much heat does 225.0 g of water release when it cools from 85.5°C to 50.0°C? Ente

Sergio [31]

The answer is 33400J

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2 years ago

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Carbon dating of small bits of charcoal used in cave paintings has determined that some of the paintings are from 10000 to 30000

Andru [333]

The age of painting was determined from the decay kinetics of the radioactive Carbon -14 present in the painting sample.

Given that the half life of Carbon-14 is 5730 years.

Radioactive decay reactions follow first order rate kinetics.

Calculating the decay constant from half life:

λ $= \frac{0.693}{t_{1/2} }$

= $\frac{0.693}{5730 yr}$ = $1.21*10^{-4}yr^{-1}$

Setting up the radioactive rate equation:

$ln\frac{A_{t} }{A_{0} } =-kt$

Where $A_{t} = Activity after time t = 0.80microCi$

$A_{t} = initial activity = 6.4microCi$

k = decay constant = $1.21*10^{-4}yr^{-1}$

$ln\frac{0.80uCi}{6.4uCi} =-(1.21*10^{-4}yr^{-1})t$

ln 0.125 = $-(1.21*10^{-4}yr^{-1})t$

-2.079= $-(1.21*10^{-4}yr^{-1})t$

t= $\frac{2.07944}{1.21*10^{-4} } yr$

= 17185 years

t = 17185 years

Therefore age of the painting based in the radiocarbon -14 dating studies is 17185 years

6 0

2 years ago

ethylene glycol used in automobile antifreeze and in the production of polyester. The name glycol stems from the sweet taste of

Luden [163]

Answer: The empirical and molecular formula for the given organic compound is $CH_3O$ and $C_4H_{12}O_4$

Explanation:

The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:

$C_xH_yO_z+O_2\rightarrow CO_2+H_2O$

where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.

We are given:

Mass of $CO_2=9.06g$

Mass of $H_2O=5.58g$

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 9.06 g of carbon dioxide, $\frac{12}{44}\times 9.06=2.47g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18g of water, 2 g of hydrogen is contained.

So, in 5.58 g of water, $\frac{2}{18}\times 5.58=0.62g$ of hydrogen will be contained.

Mass of oxygen in the compound = (6.38) - (2.47 + 0.62) = 3.29 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{2.47g}{12g/mole}=0.206moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{0.62g}{1g/mole}=0.62moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{3.29g}{16g/mole}=0.206moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.206 moles.

For Carbon = $\frac{0.206}{0.206}=1$

For Hydrogen = $\frac{0.62}{0.206}=3$

For Oxygen = $\frac{0.206}{0.206}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H : O = 1 : 3 : 1

Hence, the empirical formula for the given compound is $C_1H_{3}O_1=CH_3O$

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

$n=\frac{\text{molecular mass}}{\text{empirical mass}}$

We are given:

Mass of molecular formula = 124 amu = 124 g/mol

Mass of empirical formula = 31 g/mol

Putting values in above equation, we get:

$n=\frac{124g/mol}{31g/mol}=4$

Multiplying this valency by the subscript of every element of empirical formula, we get:

$C_{(1\times 4)}H_{(3\times 4)}O_{(1\times 4)}=C_4H_{12}O_4$

Thus, the empirical and molecular formula for the given organic compound is $CH_3O$ and $C_4H_{12}O_4$

3 0

2 years ago