Answer:
19.9 mol
Explanation:
Use <em>Avogadro’s number</em> to convert formula units of CaI₂ to moles of CaI₂.
1 mol CaI₂ ≡ 6.022 × 10²³ formula units CaI₂
Moles of CaI₂ = 1.20 × 10²⁵ × (1 /6.022 × 10²³)
Moles of CaI₂ = 19.9 mol
Answer:
A penny dissolves in hydrochloric acid if the copper coating is filed down in several spot... ... When The Zinc In A Certain Penny Dissolves, The Total Volume Of Gas ... is filed down in several spots (so that the hydrochloric acid can reach the zinc). The reaction between the acid and the zinc 2H+(aq)+Zn(s)→H2(g)+Zn2+(aq) .
Answer:
Hygroscopic
Explanation:
An hygroscopic substance is one that absorbs moisture from the atmosphere and becomes wet. Their ability to remove water from air is less than that of deliquescent substances. Most of the solid hygroscopic substances forms pasty substances and not solutions like the deliquescent compounds.
Examples are sodium trioxonitrate(v), copper(ii) oxide e.t.c
Efflorescence compounds gives off their water of crystallization to the atmosphere.
Explanation:
option option B is the correct answer of given statement helium-4(He)=2
<span>Well it depends on percentage by what, but I'll just assume that it's percentage by mass.
For this, we look at the atomic masses of the elements present in the compound.
Cu has an atomic mass of 63.546 amu
Fe has 55.845 amu
and S has 36.065 amu
Since there are 2 molecules of Sulfur for each one of Cu and Fe, we'll multiply the Sulfur atomic weight by 2 to obtain 72.13 amu
So we have not established the mass of the compound in amus
63.546 + 55.845 + 72.13 = 191.521
That is the atomic mass of Chalcopyrite. and Iron's atomic mass is 55.845
So to get the percentage, or fraction of iron, we take 55.845 / 191.521
Which comes out to 29.15% by mass
Mass of the sample is not needed for this calculation, but since the question mentions it I would go ahead and check if the question isn't also asking for the mass of Iron in the sample as well, in which case you just find the 29.15% of 67.7g</span>
