Answer 19.9g. I’ve took the test last week at my uncle randy’s house
Answer:
Hydrogen H₂ will be the limiting reagent.
The excess reactant that will be left after the reaction is 3.45 moles.
4.3 moles of water can be produced.
Explanation:
The balanced reation is:
2 H₂ + O₂ → 2 H₂O
By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of each compound participate in the reaction:
- H₂: 2 moles
- O₂: 1 mole
- H₂O: 2 moles
To determine the limiting reagent, you can use a simple rule of three as follows: if by stoichiometry 1 mole of O₂ reacts with 2 moles of H₂, how much moles of H₂ will be needed if 5.6 moles of O₂ react?

moles of H₂= 11.2 moles
But 11.2 moles of H₂ are not available, 4.3 moles are available. Since you have less moles than you need to react with 5.6 moles of O₂, <u><em>hydrogen H₂ will be the limiting reagent</em></u> and oxygen O₂ will be the excess reagent.
Then you can apply the following rules of three:
- If by reaction stoichiometry 2 moles of H₂ react with 1 mole of O₂, 4.3 moles of H₂ will react with how many moles of O₂?

moles of O₂= 2.15 moles
The excess reactant that will be left after the reaction can be calculated as:
5.6 moles - 2.15 moles= 3.45 moles
<u><em>The excess reactant that will be left after the reaction is 3.45 moles.</em></u>
- If by reaction stoichiometry 2 moles of H₂ produce 2 moles of H₂O, 4.3 moles of H₂ produce how many moles of H₂O?

moles of H₂O= 4.3 moles
<u><em>4.3 moles of water can be produced.</em></u>
Answer: The percent composition of oxygen is 54.5%
Explanation:
Below I have attached my work through, but essentially the percent composition relies on finding the mass of the oxygens and dividing it by the mass of the whole compound. The masses of the elements can be found on the periodic table and added together to get a mass of the whole compound- ascorbic acid. Then, you turn this proportion into a percent by multiplying by 100%.
the second option is the correct answer i PROMISE
Answer:
The period number tells which is the highest energy level occupied by the electrons.
Explanation:
- The period number (denoted by n) is the outer energy level that is occupied by electrons in an atom.
- The period number that an element is in, is the number of energy levels that the element has.
- When we move across a period from left to right in a periodic table the number of electrons in atoms increases within the same orbit.