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Not kidding you the answer is, more than one
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.
Answer:
1
atom of
Cu
has a mass of
1.055
×
10
−
22
g
.
Explanation:
1 atom Cu
⋅
1 mol Cu
6.022
×
10
23
atoms Cu
⋅
63.546 g Cu
1 mol Cu
=
1.055
×
10
−
22
g Cu
1 atom of copper must be converted in moles to express it as a quantity that can be converted into grams (our second step).
Avogadro's Number
(
1 mole
=
6.022
×
10
23
particles
)
and the relative atomic mass of copper
(
1 mole of copper = 63.546 g
)
are the equalities required to make this conversion.
Explanation:
<span>this is a limiting reagent problem.
first, balance the equation
4Na+ O2 ---> 2Na2O
use both the mass of Na and mass of O2 to figure out how much possible Na2O you could make.
start with Na and go to grams of Na2O
55.3 gNa x (1molNa/23.0gNa) x (2 molNa2O/4 molNa) x (62.0gNa2O/1molNa2O) = 75.5 gNa2O
do the same with O2
64.3 gO2 x (1 molO2/32.0gO2) x (2 molNa2O/1 mol O2) x (62.0gNa2O/1molNa2O) = 249.2 g Na2O
now you must pick the least amount of Na2O for the one that you actually get in the reaction. This is because you have to have both reacts still present for a reaction to occur. So after the Na runs out when it makes 75.5 gNa2O with O2, the reaction stops.
So, the mass of sodium oxide is
75.5 g</span>