Answer:
Answer: The mass of product left in the test tube will be less than the initial measured mass of the reactants.
Explanation: This is because one of the products of the reaction is a gas (hydrogen) and it escapes as the reaction happens in an open system.
This is the reaction,
Mg(s) + 2HCl(aq) --------> MgCl2(aq) + H2(g)
So, evidently, only MgCl2 is left in the reaction test tube together with unreacted reactants.
But, the hydrogen gas that escapes accounts for the lesser mass at the end of the reaction.
The mass in the test tube at the end of the reaction +
the mass of Hydrogen gas that escapes = the mass of reactants before the reaction; consolidating the law of conservation of mass.
She will use the periodic table of elements to not only find out the chemical symbols of the elements written within the name, but also to check whether or not the elements are metals and or nonmetals, from this determine the ionic charges if needed for metals, and for metals that have more than one ionic charge, use a Roman numeral to represent the ionic charge that she would be using in writing the chemical formula of the compound.
You only can calculate the empirical formula with that information. I can not guarantee the empirical formula is going to be the same than the molecular formula. To be able to calculate the molecular formula you need the molecular mass or other information.
58.8/12= C = 4.9 => 4.9/1.96 = 2.5 => 2.5*2= 5
9.8/1= H = 9.8 => 9.8/1.96 = 5 => 5* 2= 10
31.4/16=O = 1.96 =>1.96/1.96 = 1 => 1*2 =2
empirical formula C5H10O2
CO2
The symbol how you write
<span>C7H8
First, lookup the atomic weight of all involved elements
Atomic weight of carbon = 12.0107
Atomic weight of hydrogen = 1.00794
Atomic weight of oxygen = 15.999
Then calculate the molar masses of CO2 and H2O
Molar mass CO2 = 12.0107 + 2 * 15.999 = 44.0087 g/mol
Molar mass H2O = 2 * 1.00794 + 15.999 = 18.01488 g/mol
Now calculate the number of moles of each product obtained
Note: Not interested in the absolute number of moles, just the relative ratios. So not going to get pedantic about the masses involved being mg and converting them to grams. As long as I'm using the same magnitude units in the same places for the calculations, I'm OK.
moles CO2 = 3.52 / 44.0087 = 0.079984
moles H2O = 0.822 / 18.01488 = 0.045629
Since each CO2 molecule has 1 carbon atom, I can use the same number for the relative moles of carbon. However, since each H2O molecule has 2 hydrogen atoms, I need to double that number to get the relative number of moles for hydrogen.
moles C = 0.079984
moles H = 0.045629 * 2 = 0.091258
So we have a ratio of 0.079984 : 0.091258 for carbon and hydrogen. We need to convert that to a ratio of small integers. First divide both numbers by 0.079984 (selected since it's the smallest), getting
1: 1.140953
The 1 for carbon looks good. But the 1.140953 for hydrogen isn't close to an integer. So let's multiply the ratio by 1, 2, 3, 4, ..., etc and see what each new ratio looks like (Effectively seeing what 1, 2, 3, 4, etc carbons look like)
1 ( 1 : 1.140953) = 1 : 1.140953
2 ( 1 : 1.140953) = 2 : 2.281906
3 ( 1 : 1.140953) = 3 : 3.422859
4 ( 1 : 1.140953) = 4 : 4.563812
5 ( 1 : 1.140953) = 5 : 5.704765
6 ( 1 : 1.140953) = 6 : 6.845718
7 ( 1 : 1.140953) = 7 : 7.986671
8 ( 1 : 1.140953) = 8 : 9.127624
That 7.986671 in row 7 looks extremely close to 8. I doubt I'd get much closer unless I go to extremely high integers. So it looks like the empirical formula for toluene is C7H8</span>