The answer is 267.93 g
Molar mass of CaBr2 is the sum of atomic masses of Ca and Br:
Mr(CaBr2) = Ar(Ca) + 2Ar(Br)
Ar(Ca) = 40 g/mol
Ar(Br) = 79.9 g/mol
Mr(CaBr2) = 40 + 2 * 79.9 = 199.8 g/mol
The percentage of Br in CaBr2 is:
2Ar(Br) / Mr(CaBr2) * 100 = 2 * 79.9 / 199.8 * 100 = 79.98%
Now make a proportion:
x g in 79.98%
335 g in 100%
x : 79.98% = 335 g : 100%
x = 79.98% * 335 g : 100%
x = 267.93 g
Answer:
2Cu + S ~~~> Cu2S Copper (C) reacts with sulfur (S) to form copper sulfide as shown in the equation. A scientist adds 12.7 grams of Cu to 3.2 grams of S to start the reaction.
Explanation:
To rank the effective nuclear charge Z* experienced by a valence electrons of a set of atoms that belong to a same period, you only need to apply the rule of trend: it increases as you move from left to right in the period.
So, lets do it for these atoms: P, Al, Si, Cl
The belong to a same period and the order is Al, Si, P, Cl (just see a periodic table). So the rank is Al < Si < P < Cl
Now, lets do it for these atoms:, Be, Ne, O, C
They belong to the second period. The order is Be, C, O, Ne
So, the rank is Be < C < O < Ne.
C is the answer hope the answer is right