00:01
For question 40, a solution contains 50 milligrams of a drug for every 100 milliliters.
00:09
The total volume of the saline is 40 milliliters.
00:17
So how many grams of drug will be needed in this solution? well, we'll start with the 40 milliliters and recognize that there are 500 milligrams for every 100 milliliters and there's 1 gram for every 1000 milligrams and we get 0 .2 grams.
00:52
Then for question 41 an unknown element contains two isotopes with the given masses and given percentages what is the atom's mass and identity of the unknown element well it's mostly firstly, isotope 1, which is 38 .964 amu.
01:19
So the average mass needs to be pretty close to 38 .964, a little bit greater than that, because the second isotope is 40 .962.
01:33
To calculate the actual average, we take the mass of the first isotope, 38 .964, multiply it by its fractional abundance, 93 .3, expressed as a fraction, is 0 .933, and add to that the mass of the second isotope, 40 .962, multiplied by its fractional abundance, 0 .067, and we get 39 .098 amu, and 39 .098 amu, if we go to the periodic table, is potassium.
02:39
And then for the next question, the scientists reacted so many moles of the two reactants.
02:48
What is the limiting reaction? so our chemical reaction is 2bicl3 with 3 h2s to produce bi2s3 and 6 hcl.
03:11
To identify the limiting reactant, we need to identify the reactant that produces the least amount of product...