Chemistry, 18.09.2019 21:00 tiffanydowell13

Which is an example of a chemical change

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Answer from: daedae96

Answer : The correct option is, (C) metal corroding in salt water.

Explanation :

Chemical change : It is a change where changes occurs in the chemical composition and thus resulting in the formation of new compound or substance. It is an irreversible reaction.

The indication of chemical changes are :

Formation of gas bubbles.

Formation of precipitate.

Change in color.

Change in temperature.

Change in volume.

Change in smell or taste.

Evolution of heat, light and sound.

Physical change : It is a change in which shape and size of a substance changes. In this there is no change in the chemical composition of the substance and no new substance is forming. It is a reversible reaction.

The indication of chemical changes are :

Change in shape.

Change in form.

Change in size.

Change in phase.

(A) Mixing of poster colors : It is a physical change because only changes takes place in the phase from liquid phase to vapor phase.

(B) Formation of clouds : It is a physical change because only changes takes place in the phase from vapor phase to liquid phase.

(D) Sugar dissolving in water : It is a physical change because only changes takes place in the phase from solid phase to liquid phase.

(E) Separating salt from seawater : It is a physical change because only changes takes place in the phase from liquid phase to solid phase.

Hence, the correct option is, (C) metal corroding in salt water.

Answer from: Quest

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

= 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g

Answer from: Quest

i just learnt this recently but i need to look through my notes again

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