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klasskru [66]
4 years ago
14

Classify each of the following as an exothermic or an endothermic reaction:

Chemistry
2 answers:
ira [324]4 years ago
6 0
Equation a. C3H8(g) + O2(g) → CO2(g) + H2O(g) + 2220 kj
is endothermic. + 2220 kj
Equation b. 2 Na(s) + Cl2(g) → 2 NaCl(s) + 819kJ
is also endothermic since the overall energy change is positive. + 819kJ
The equation c. PCl5(g) + 67kj → PCl3(g) + Cl2(g) is endothermic since it requires anergy to proceed.
BigorU [14]4 years ago
5 0

Answer:

Reaction A) is exothermic

Reaction B) is exothermic

Reaction C) is endothermic.

Explanation:

Hi, by definition an exothermic reaction is the one that generates heat as it occurs. An endothermic reaction on the other hand, consumes heat from the environment as it happens.

<u>This can be seen, when energy is put as a reactant in the equation. When it appears as a procuct the reaction is exothermic.</u>

Being all that said:

  • Reaction A) is exothermic
  • Reaction B) is exothermic
  • Reaction C) is endothermic.
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Is evaporation of water a physical change or a chemical change? explain your answer?
Olin [163]
Chemical because it would be impossible to get the evaporated water and turn it back into it's original substance.
8 0
3 years ago
What are the four points of food safety?​
KatRina [158]

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Hope this helps! If you need more help or have any questions just message me! :)

7 0
3 years ago
A calorimeter contains 100 g of water at 39.8 ºC. A 8.23 g object at 50 ºC is placed inside the calorimeter. When equilibrium ha
Tju [1.3M]
When equilibrium has been reached so, according to this formula we can get the specific heat of the unknown metal and from it, we can define the metal as each metal has its specific heat:

Mw*Cw*ΔTw = Mm*Cm*ΔTm

when 
Mw → mass of water
Cw → specific heat of water
ΔTw → difference in temperature for water 

Mm→ mass of metal
Cw→ specific heat of the metal
ΔTm → difference in temperature for metal

by substitution:

100g * 4.18 * (40-39.8) = 8.23 g * Cm * (50-40)

∴ Cm = 83.6 / 82.3 = 1.02 J/g.°C

when the Cm of the Magnesium ∴ the unknown metal is Mg
6 0
3 years ago
Does the density of ice affect the melting rate of ice, or does adding objects affect melting rates? I'm going to need evidence
kotykmax [81]
The density of ice does not affect the melting rate. But, adding an object does affect the melt rate. The reason this is is because when there is an object, there is less to melt. Hence, affecting the melting rate.
7 0
3 years ago
Read 2 more answers
4Cr(s)+3O2(g)→2Cr2O3(s) calculate how many grams of the product form when 21.4 g of O2 completely reacts
weqwewe [10]

Answer:

= 67.79 g

Explanation:

The equation for the reaction is;

4Cr(s)+3O2(g)→2Cr2O3(s)

The mass of O2 is 21.4 g, therefore, we find the number of moles of O2;

moles O2 = 21.4 g / 32 g/mol

                =0.669 moles

Using mole ratio, we get the moles of Cr2O3;

moles Cr2O3 = 0.669 x 2/3

                       =0.446 moles

but molar mass of Cr2O3 is 151.99 g/mol

Hence,

The mass Cr2O3 = 0.446 mol x 151.99 g/mol

                            <u> = 67.79 g </u>

6 0
3 years ago
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