How much Sr(OH)2 • 8 H2O (M = 265.76) is needed to

1 answer:

3 0

First, you need to find the number of moles of OH⁻ in a 250mL solution of 0.100M OH⁻. To do this, multiply 0.250L by 0.100M to get 0.025mol OH⁻. Then you use the fact that 1 mole of Sr(OH₂)·8H₂O contains 2 moles of OH⁻ which means that 0.0125mol of Sr(OH)₂·8H₂O contains 0.025mol OH⁻ (0.025/2=0.0125). Then to find the amount of Sr(OH)₂·8H₂O is needed you multiply its molar mass (265.76g/mol) by 0.0125mol to get 3.322g.
Therefore you need 3.322g of Sr(OH)₂·8H₂O.

I hope that helps. Let me know if anything is unclear.

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How many molecules of H2O and O2 is present in 8.5g of H2O?

Igoryamba

Answer:

2.8 x 10²³ molecules H₂O

1.4 x 10²³ molecules O₂

Explanation:

First, you will need the balanced chemical equation for the formation of water:

2H₂ + O₂ -> 2H₂O

This will help in determining the mole ratios between water and oxygen, which we will need later.

Let's first calculate the number of H₂O (water) molecules. This will require stoichiometry. We are also given the mass, so we must convert mass into moles, then moles into molecules. mass -> moles -> molecules

8.5 g H₂O x (1 mol H₂O/18.01528 g H₂O) x (6.02 x 10²³ molecules H₂O/1 mol H₂O) = 2.8404 x 10²³ molecules H₂O

Rounded to 2 significant digits: 2.8 x 10²³ molecules H₂O

Now, to find the molecules of water, we can begin with the same stoichiometric equation, but before we convert to molecules, we will have to convert moles of water to moles of oxygen. This is where we will use the mole ratio of water to oxygen we got from the balanced chemical equation earlier. 2H₂O:1O₂

8.5 g H₂O x (1 mol H₂O/18.01528 g H₂O) x (1 mol O₂/2 mol H₂O) x (6.02 x 10²³ molecules O₂/1 mol O₂) = 1.4202 x 10²³ molecules O₂

Rounded to 2 significant digits: 1.4 x 10²³ molecules O₂

3 0

3 years ago

An aqueous solution of perchloric acid is standardized by titration with a 0.191 M solution of barium hydroxide. If 13.8 mL of b

WARRIOR [948]

Answer:

Molarity of $HClO_{4}$ solution is 0.311 M