Chemistry, 30.07.2019 06:30 Niah628

Which of these is an example of a physical change? sugar, when heated, producing carbon dioxide and water solid ice, when heated, turning into liquid water sodium, when exposed to chlorine, forming sodium chloride aluminum, when heated in air, forming aluminum oxide

Answers: 2

Show answers

Answers

Answer from: jflakes5108

Solid ice melting is a physical change. If it doesn't make anything new, it's physical.

Answer from: JJJuliedavis

Option (b) is the correct answer.

Explanation:

When there is no change in chemical composition of a substance then this change is known as physical change.

Where as when there is change in chemical composition of a substance then it is known as chemical change.

When sugar is heated, it results in the formation of carbon dioxide and water. This means that composition of sugar has changed thus, it is a chemical change.

When solid ice is melted, it turns into liquid. This shows that only state of water has changed. There is no change in chemical composition because when we freeze water then again liquid water changes into solid ice. Thus, it is a physical change.

When sodium reacts with chlorine then the reaction is as follows.

$2Na + Cl_{2} \rightarrow 2NaCl$

It shows that chemical composition of sodium has changed due to the formation of sodium chloride. Thus, it is a chemical change.

Also, when aluminium is is heated in air then it results in the formation of aluminium oxide. This means that the chemical composition of aluminium has changed.

Hence, we can conclude that out of the given options, solid ice, when heated, turning into liquid water is an example of a physical change.

Answer from: Quest

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 : $4x (s) + 3o_{2} (g) \rightarrow 2x_{2}o_{3} (s) h rxn = -600 kj/mol$

equation 2 : $2x (s) + 3cl_{2} (g) \rightarrow 2xcl_{3} (s) h rxn = -800 kj/mol$

equation 3 : $4xcl_{3} (s) + 3o_{2} (g) \rightarrow 2x_{2}o_{3} (s) + 6cl_(2} h rxn = -200 kj/mol$

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 : $4xcl_{3} (s) \rightarrow 4x (s) + 6cl_{2} ( h rxn = (+800) \times 2 kj/mol$

let us add equation 1 & 4

$4x (s) + 3o_{2} (g) \rightarrow 2x_{2}o_{3} (s) h rxn = -600 kj/mol$

$4xcl_{3} (s) \rightarrow 4x (s) + 6cl_{2} ( h rxn = (+1600) kj/mol$

$4xcl_{3} )s) + 3o_{2} \rightarrow 2x_{2}o_{3} (s) + 6cl_{2} (g) h rxn = (+1000) kj/mol$

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

Answer from: Quest

wanswer:

explanation:

Another question on Chemistry

Chemistry, 22.06.2019 04:00

Two nitro no2 groups are chemically bonded to a patch of surface. they can't move to another location on the surface, but they can rotate (see sketch at right). it turns out that the amount of rotational kinetic energy each no2 group can have is required to be a multiple of ε, where =ε×1.010−24 j. in other words, each no2 group could have ε of rotational kinetic energy, or 2ε, or 3ε, and so forth — but it cannot have just any old amount of rotational kinetic energy. suppose the total rotational kinetic energy in this system is initially known to be 32ε. then, some heat is removed from the system, and the total rotational kinetic energy falls to 18ε. calculate the change in entropy. round your answer to 3 significant digits, and be sure it has the correct unit symbol.

Answers: 2

Answer

Chemistry, 22.06.2019 05:50

According to coulomb's law, how would the electrical force between particles change if the product of their electrical charge increased?

Answers: 1

Answer

Chemistry, 22.06.2019 13:00

Adepositional also feature that forms where a stream enters a lake or an ocean is a

Answers: 2

Answer

Chemistry, 22.06.2019 22:10

What is the indicator of the number of ions in solution? the amount of conductivity the amount of precipitate the amount of solute added