B is true because liquids are still more compact than gases, although they are loose, they aren't completely free. They also don't have a definite volume, making them assume the shape of their container. As for compression, liquids are harder to compress compared to gases.
The steam releases 39.9 kJ when it condenses..
The steam condenses and transfers its energy to the skin.
<em>q = m</em>Δ<em>H</em>_cond = 17.7 g × (-2257 J/1 g) = -39 900 kJ = -39.9 kJ
The negative sign shows that the steam is releasing energy
Answer:
(a) oxygen
(b) 154g (to 3sf)
(c) 79.9% (to 3sf)
Explanation:
mass (g) = moles × Mr/Ar
note: eqn means chemical equation
(a)
moles of P = 84.1 ÷ 30.973 = 2.7152 moles
moles of O2 = 85÷2(16) = 2.65625 moles
Assuming all the moles of P is used up,
moles of O2 / moles of phosphorus = 5/4 (according to balanced chemical eqn)
moles of O2 required = 5/4 × 2.7152moles = 3.394 moles (more than supplied which is 2.65625moles)
therefore there is insufficient moles of O2 and the limiting reactant is oxygen.
(b)
moles of P2O5 produced
= 2/5 (according to eqn) × 2.7152
= 1.08608moles
mass of P2O5 produced
= 1.08608 × [ 2(30.973) + 5(16) ]
= 154.164g
= approx. 154g to 3 sig. fig.
(c)
% yield = actual/theoretical yield × 100%
= 123/154 × 100%
= 79.870%
= approx. 79.9% (to 3sf)
<span>number of moles are the amount of substance of an element .
number of moles can be calculated as follows;
number of moles = mass present / molar mass of element
molar mass of Ar - 40 g/mol
number of moles of Ar = 22 g / 40 g/mol = 0.55 mol .
there are 0.55 mol of Ar</span>
Answer:
B) 2Crº + 6e- --> 2Cr3+
Explanation:
The process of oxidation is where electrons are lost. Thus, out of the 2 ions that change charge(Cr and Cu), we must choose the one where the oxidation number increases(which means electrons are lost). Cr goes from an oxidation number of 0 to an oxidation number of 3+, while Cu goes from an oxidation number of 2+ to 0. Thus, we are looking at the half reaction for Cr. Half reactions never have subtracting electrons, so the answer must be B. I am assuming that last plus should be a -->
