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svet-max [94.6K]
2 years ago
9

A goldsmith melts 12.4 grams of gold to make a ring. The temperature of the gold rises from 26°C to 1064°C, and then the gold me

lts completely. If gold’s specific heat is 0.1291 joules/gram degree Celsius and its heat of fusion is 63.5 joules/gram, how much energy is gained by the gold?
The gold gains a total of ____ joules of energy.

I was given this by somebody. No idea what to do with this.
QJ=(12.4g*(1064-26)°C*0.1291J/g/°C)+(12.4g*63.5J)
Chemistry
1 answer:
Oduvanchick [21]2 years ago
3 0

Answer:

The gold gains a total of 2.468 kilo-joules of energy.

Explanation:

Total heat or energy gained by the gold is equal to heat applied and heat required to melt the gold completely.

Total energy = Q+ Q'

Heat of fusion of gold =\Delta H_{fus} =63.5 joules/gram

Mass of gold melted ,m= 12.5 g

Specific heat of gold ,c= 0.1291 joules/gram °C

Change in temperature = ΔT = 1064°C - 26°C = 1038 °C

Heat of applied to the gold = Q

Q=mc\Delta T

Q'=\Delta H_{fus}\times m

Total energy = Q+ Q'

=12.5 g\times 0.1291 joules/gram ^oC\times 1038 ^oC+63.5 joules/gram\times 12.5 g

= 2,468.82 Joule= 2.468 kilo-Joule

The gold gains a total of 2.468 kilo-joules of energy.

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50 kg of N2 gas and 10kg of H2 gas are mixed to produce NH3 gas calculate the NH3gas formed. Identify the limiting reagent in th
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Answer:

1. H2 is the limiting reactant.

2. 56666.67g ( i.e 56.67kg) of NH3 is produced.

Explanation:

Step 1:

The equation for the reaction. This is given below:

N2 + H2 —> NH3

Step 2:

Balancing the equation.

N2 + H2 —> NH3

The above equation can be balanced as follow :

There are 2 atoms of N on the left side and 1 atom on the right side. It can be balance by putting 2 in front of NH3 as shown below:

N2 + H2 —> 2NH3

There are 6 atoms of H on the right side and 2 atoms on the left side. It can be balance by putting 3 in front of H2 as shown below

N2 + 3H2 —> 2NH3

Now the equation is balanced.

Step 3:

Determination of the masses of N2 and H2 that reacted and the mass of NH3 produced from the balanced equation. This is illustrated below:

N2 + 3H2 —> 2NH3

Molar Mass of N2 = 2x14 = 28g/mol

Molar Mass of H2 = 2x1 = 2g/mol

Mass of H2 from the balanced equation = 3 x 2 = 6g

Molar Mass of NH3 = 14 + (3x1) = 14 + 3 = 17g/mol

Mass of NH3 from the balanced equation = 2 x 17 = 34g

From the balanced equation above,

28g of N2 reacted with 6g of H2 to produce 34g of NH3

Step 4:

Determination of the limiting reactant. This is illustrated below:

N2 + 3H2 —> 2NH3

Let us consider using all the 10kg (i.e 10000g) of H2 to see if there will be any left of for N2.

From the balanced equation above,

28g of N2 reacted with 6g of H2.

Therefore, Xg of N2 will react with 10000g of H2 i.e

Xg of N2 = (28 x 10000)/6

Xg of N2 = 46666.67g

We can see from the calculations above that there are leftover for N2 as only 46666.67g reacted out of 50kg ( i.e 50000g) that was given. Therefore, H2 is the limiting reactant.

Step 5:

Determination of the mass of NH3 produced during the reaction. This is illustrated below:

N2 + 3H2 —> 2NH3

From the balanced equation above,

6g of H2 reacted to produce 34g of NH3.

Therefore, 10000g of H2 will react to produce = ( 10000 x 34)/6 = 6g of 56666.67g of NH3.

Therefore, 56666.67g ( i.e 56.67kg) of NH3 is produced.

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Answer:

The answer to your question is below

Explanation:

                                ionic compounds                  covalent compounds

1.- Mass                          it does not depend on the type of compound

2.- Conductivity      -conduct electricity               - do not conduct electricity

                                  in solution.

3.- Color                  - Shiny                                     - opaque

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5.- Boiling point     - high                                        - lower than ionic compounds

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M = number of moles of solute / volume of solution in liters

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number of moles of solute = 100 g / 119.37 g/mol = 0.838 mol

using density of water = 1 g/ ml => 1,000,000,000 g = 1,000,000 liters

M = 0.838 / 1,000,000 = 8.38 * 10^ - 7 M <----- answer

Molality, m

m = number of moles of solute / kg of solvent

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mole fraction of solute, X solute

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number of moles of solution = number of moles of solute + number of moles of solvent

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number of moles of solution = 0.838 moles + 55,508,435 moles = 55,508,436 moles

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% = (mass of solute / mass of solution) * 100 = (100g / 1,000,000,100 g) * 100 =

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