Answer:
When the solution (with phenolphthalein) changes to colorless
Explanation:
When titrating with HCl is common to add phenolphthalein as an acid-base indicator.
Phenolphthalein is pink or fucsia when added into a basic solution. On the other hand when it is in acid solutions, is colorless.
So, when titrating, the NaOH solution will be initialy pink due to the phenolphthalein and when reaching the equivalence point, that color will fade out into colorless. This is how you know you hace reached the equivalent point.
The C-H bonds (in methane) break and so do the O-O bonds (in oxygen)
<span>The reaction is :</span>
CH4 +2O2 -> CO2 + 2H2O
Answer:
match emit 350 J light energy.
Explanation:
By law of conservation of energy, total energy before and after reaction for an isolated system remains constant.
Total energy for unlit match = 1000 j
When it burns type of energy released
thermal energy = 400 j
light energy --> it value is unknown which we have to find
also remaining match has 250 joule of chemical energy
applying law of conservation of energy
energy before match was unlit = energy after match was lit
1000 j = thermal energy + light energy + chemical energy of remaining match
1000 J = 400 J + light energy + 250 J
light energy = 1000 J - 400J - 250J
light energy = 350 J
Thus, match emit 350 J light energy.
Explanation:
protons and neutrons.....
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