Answer:
The answer to your question is: letter B
Explanation:
Reaction
Cr2O3(s) + 3CCl4(l) ⇒ 2CrCl3(s) + 3COCl2(g)
From the information given and the reaction, we can conclude that:
Green solid = Cr2O3 (s) "s" means solid
Colorless liquid = CCl4 (l) "l" means liquid and is the other reactant
Purple solid = CrCl3(s) CrCl3 is purple and "s" solid
Then, as a green specks remains it means that the excess reactant is Cr2O3, so, CCl4 is the limiting reactant.
Molarity is defined as the number of moles of solute in 1 L of the solution.
Since the mass of the solute has been given we have to obtain the number of moles of solute
Number of moles = mass / molar mass
So we need to convert the mass to number of moles by dividing the mass by its molar mass.
The volume of the solution needs to be given in L but it has been measured in ml. Therefore volume in mL should be converted to L.
The molarity is found by dividing the number of moles by volume of solution in L
Answer is C)
<h3>Explanation</h3>
Find the oxidation state for each element.
The oxidation state of H is +1 in most compounds.
- The S atom in H₂S is bonded to two H atoms. The oxidation state of S in H₂S will be -(2 × (+1)) = -2.
- Two O atom in H₂O₂ are bonded to two H atoms. On average, the oxidation state for each O atom in H₂O₂ will be - 1/2 × (2 × (+1)) = -1.
- S has an oxidation state of 0 when it is not bonded to any other element;
- The O atom in H₂O is bonded to two H atoms. The oxidation state of O in H₂O will be -(2 × (+1)) = -2.
Changes in oxidation states:
- S: from -2 to 0.
- O: from -1 to -2.
Each S atom will reduce two O atoms. There are two O atoms in each H₂O₂ molecule. There's only one S atom in each H₂S molecule. As a result, pairing one H₂O₂ with one H₂S will balance the change in oxidation state.
Each H₂O₂ contains two O atoms. The two O atoms will produce two H₂O molecules. Each H₂S molecule will lead to one S molecule. Thus the coefficient for H₂O will be two and the coefficient for the rest three species will be one.
Answer:
2.04 x 10⁻⁶ moles H₂O
Explanation:
To find the moles H₂O, you need to multiply the given value by Avogadro's Number. This number is a ratio between molecules and moles, thus granting you the way to convert between both units. It is important to arrange the ratio in a way that allows for the cancellation of units. The final answer should have 3 sig figs to match the sig figs of the given value (1.23 x 10¹⁸ molecules).
Avogadro's Number:
6.022 x 10²³ molecules = 1 mole
1.23 x 10¹⁸ molecules H₂O 1 mole
--------------------------------------- x ------------------------------------- =
6.022 x 10²³ molecules
= 2.04 x 10⁻⁶ moles H₂O
