Mass of strontium = 88 g
Atomic mass of Sr = 87.62 u
Moles = mass /atomic mass
Moles of Sr = 88 / 87.62 = 1.004
Mass of bromine = 160 g
Atomic mass of Br = 79.904 u
Molar mass of Br₂ = 79.904 x 2 = 159.808 g/mol
Moles = mass /molar mass
Moles of Br₂ = 160 / 159.808 = 1.001
The balanced chemical equation of the reaction between strontium and bromine:
Sr(s) + Br₂(l) = SrBr₂
The molar ratio between Br₂ and SrBr₂ is 1:1
So the moles of SrBr₂ produced from 1.001 moles of Br₂ is 1.001.
Moles = mass /molar mass
Mass = moles x molar mass
Molar mass of SrBr₂ = 247.4280 g/mol
Mass = 1.001 mol x 247.4280 g/mol
Mass = 247.428 g
The mass of strontium bromide produced is 247.428 g.
The rate of change in the amount of silver supplied is equal to the ratio of the difference in the amount supplied to the number of years elapsed from 2005 to 2008. That is,
rate of change = (25 - 200) / (2008 - 2005) = -173/3
The answer is letter A.
Answer:
7. .........................
The six metalloids are boron, silicon, germanium, arsenic, antimony, and tellerium.
D. Is a fly shot effective in preventing the flu?
Answer A touches on the topics of economics and industrial feasibility of the flu shot.
B is more of an ethical / situational question.
C is a social question.
D is the only question which focuses on the science of microbiology and medicine.
