Chemistry, 29.09.2021 21:40 jeepjose58

HLEP NOW 5TH GRADE SCIENCE What is the main difference between a chemical and Physical change? Use examples to support your answer.

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Answer from: KillerSteamcar

Physical change

When a substance undergoes a physical change, its composition remains the same despite its molecules being rearranged.

Physical change is a temporary change.

A physical change involves very little to no absorption of energy.

Generally, physical changes do not involve the production of energy.

In a physical change, no new substance is formed.

Physical change is easily reversible i.e original substance can be recovered.

Some examples of physical change are freezing of water, melting of wax, boiling of water, etc.

Chemical change

When a substance undergoes a chemical change, its molecular composition is changed entirely. Thus, chemical changes involve the formation of new substances.

A chemical change is a permanent change.

Chemical change both physical and chemical properties of the substance including its composition

During a chemical reaction, absorption and evolution of energy take place.

Chemical changes usually involve the production of energy (which can be in the form of heat, light, sound, etc.)

A chemical change is always accompanied by one or more new substance(s).

Chemical changes are irreversible i.e. original substance cannot be recovered.

A few examples of chemical change are digestion of food, burning of coal, rusting, etc.

for more information please visit https://byjus.com/chemistry/difference-between-physical-and-chemical-change/#:~:text=A%20chemical%20change%20is%20a,i.e.%20shape%2C%20size%2C%20etc.&text=Some%20examples%20of%20physical%20change,of%20coal%2C%20rusting%2C%20etc.

Hope this helps

Answer from: Quest

i am going to put the answers in order i dint feel like typing it out so yeah

Answer from: Quest

answer: the value of enthalpy change will be -152.80 kj.

solution:

pressure = 1atm , temperature = $25^oc$ = 298 k $)0^oc=273kelvins$

$o_3+3no\rightarrow 3no_2,\delta h_{reaction}=? [/)</p><p>[tex]\delta h_{no}=90.4kj/mol$

$\delta h_{no_2}=33.85kj/mol$

$\delta h_{o_3}=142.2kj/mol$

$\delta h_{reaction}=\sum \delta h_{products}-\sum\delta h_{reactants}=3\times\delta h_{no_2}-(3\times \delta h_{no}+\delta h_{o_3})$

$\delta h_{reaction}=33.85-(90.4+142.2)=-311.85kj/mol$

given that pressure and temperature are same in both gases , the number of moles of both gases can be determined by the ideal gas equation.

$v_{no}=12.00 l,v_{o_3}=8.50 l$

$pv_{no}=n_{no}rt=1atm \times 12.00 l=n_{no}\times 0.0821 atml/k mol \times 298 k$

$n_{no}=0.49 moles$

$pv_{o_3}=n_{o_3}rt=1atm \times 8.50 l=n_{o_3}\times 0.0821 atml/k mol \times 298 k$

$n_{o_3}=0.34 moles$

according to reaction 3 moles no are reacting with 1 mol of $o_3$ ,then 0.49 mol of no will react with $\frac{1}{3}\times 0.49$ moles of ozone that is 0.16 moles of ozone. since, no is limiting reagent and $o_3$ is an excessive reagent.

enthalpy change for the reaction between the given volumes of the gases is :

$\delta h_{reaction}\times \text{moles of no}=-311.85kj/mol\times 0.49 mol=-152.80kj/mol$

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HLEP NOW 5TH GRADE SCIENCE What is the main difference between a chemical and Physical change? Use...