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Nimfa-mama [501]
2 years ago
9

Which of the following phase changes is exothermic?

Chemistry
1 answer:
icang [17]2 years ago
8 0
Answer:

gas to solid

Explanation:

Exothermic means the release of heat. Any transformation from a less ordered to a more ordered state releases energy. This is represented by the change of a liquid to solid, gas to liquid, or gas to solid. Vise versa endothermic is the transformation from a more ordered state to a less ordered state represented by solid to liquid, liquid to gas, and solid to gas.
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What is the chemical formula of sodium carbonate?
Gekata [30.6K]

Answer:

Na2CO3 is the formula for sodium carbornate

6 0
2 years ago
Calculate the mass of water produced when 6.97 g of butane reacts with excess oxygen
andrew-mc [135]
The balanced reaction equation for the combustion of butane is as follows;
C₄H₁₀ + 13/2O₂ ---> 4CO₂ + 5H₂O 
the limiting reactant in this reaction is C₄H₁₀  This means that all the butane moles are consumed and amount of product formed depends on the amount of C₄H₁₀ used up.
stoichiometry of C₄H₁₀ to H₂O is 1:5
mass of butane used - 6.97 g
number of moles - 6.97 g / 58 g/mol = 0.12 mol
then the number of water moles produced - 0.12 mol x 5 = 0.6 mol
Therefore mass of water produced - 0.6 mol x 18 g/mol = 10.8 g
7 0
3 years ago
CaC2 + 2H2O ➞ C2H2 + Ca(OH)2
Paraphin [41]

Answer:

A. 0.5 mole of Ca(OH)₂.

B. 4.37 moles of H₂O.

Explanation:

The balanced equation for the reaction is given below:

CaC₂ + 2H₂O —> C₂H₂ + Ca(OH)₂

Next, we shall determine the mass of CaC₂ that reacted and the mass of C₂H₂ produced from the balanced equation. This can be obtained as follow:

Molar mass of CaC₂ = 40 + (12×2)

= 40 + 24

= 64 g/mol

Mass of CaC₂ from the balanced equation = 1 × 64 = 64 g

Molar mass of C₂H₂ = (12×2) + (2×1)

= 24 + 2

= 26 g/mol

Mass of C₂H₂ from the balanced equation = 1 × 26 = 26 g

SUMMARY:

From the balanced equation above,

64 g of CaC₂ reacted with 2 moles of H₂O to produce 26 g of C₂H₂ and 1 mole of Ca(OH)₂.

A. Determination of the number of mole of Ca(OH)₂ produced by the reaction of 32.0 g of CaC₂.

From the balanced equation above,

64 g of CaC₂ reacted to produce 1 mole of Ca(OH)₂.

Therefore, 32 g of CaC₂ will react to produce = (32 × 1)/64 = 0.5 mole of Ca(OH)₂.

Thus, 0.5 mole of Ca(OH)₂ were obtained from the reaction.

B. Determination of the number of mole of H₂O needed to produce 56.8 g C₂H₂.

From the balanced equation above,

2 moles of H₂O reacted to produce 26 g of C₂H₂.

Therefore, Xmol of H₂O will react to produce 56.8 g C₂H₂ i.e

Xmol of H₂O = (2 × 56.8)/26

Xmol of H₂O = 4.37 moles

Thus, 4.37 moles of H₂O is needed for the reaction.

3 0
2 years ago
The temperature of 15.71 grams of gold rises from 32°C to 1,064°C, and then the gold melts completely. If gold’s specific heat i
antoniya [11.8K]

Answer:Total energy gained by 15.71 g is 3090.6471 joules

Explanation:

Given:

Q = heat gained by the 15.71 gram mass of gold

Q=mc\Delta T +m\Delta H_{fusion}

\Delta T=(T_{final}-T_{initial})=(1064^oC-32^oC)=1032^oC

c = specific heat capacity of gold = 0.1291joules/gram^oC

m = mass of gold =15.71 g

Q=15.71 g\times 0.1291 joules/gram^oC (1032^oC) +15.71 g\times 63.5 Joules/gram

Heat gained by gold = 2093.0621 Joules + 997.585 Joules

=3090.6471 joules

6 0
3 years ago
What type of molecular model shows all the atoms and bonds in an organic molecule
ValentinkaMS [17]

Answer:

Structural formula shows the atoms and bondsin an organic compound.

Explanation:

Structural formula of methane shows

1 Carbon atom is singly bonded to 4 hydrogen atoms.

4 0
3 years ago
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