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scoundrel [369]
3 years ago
9

What mass of hbr (in g) would you need to dissolve a 3.4 −g pure iron bar on a padlock?

Chemistry
1 answer:
vivado [14]3 years ago
5 0

<u>Given:</u>

Mass of pure iron (Fe) = 3.4 g

<u>To determine:</u>

Mass of HBr needed to dissolve the above iron

<u>Explanation:</u>

Reaction between HBr and Fe is

Fe + 2HBr → FeBr₂ + H₂

Based on the reaction stoichiometry-

1 mole of Fe reacts with 2 moles of HBr

# moles of Fe = mass of Fe/atomic mass of Fe = 3.4/56 g.mol⁻¹ = 0.0607 moles

Therefore # moles of HBr = 2*0.0607 = 0.1214 moles

Molar mass of HBr = 81 g/mole

Mass of HBr = 0.1214 moles * 81 g/mole = 9.83 g

Ans: Mass of HBR required is 9.83 g

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What is the molarity of a solution that contains 87.75g of NaCI in 500.ml of solution
Brut [27]

Answer:

M = 3.0 mol/L.

Explanation:

  • We can calculate the molarity of a solution using the relation:

<em>M = (mass x 1000) / (molar mass x V)</em>

  • M is the molarity "number of moles of solute per 1.0 L of the solution.
  • mass is the mass of the solute (g) (m = 87.75 g of NaCl).
  • molar mass of NaCl = 58.44 g/mol.
  • V is the volume of the solution (ml) (V = 500.0 ml).

∴ M = (mass x 1000) / (molar mass x V) = (87.75 g x 1000) / (58.44 g/mol x 500.0 ml) = 3.0 mol/L.

6 0
3 years ago
A mixture containing nitrogen and hydrogen weighs 3.49 g and occupies a volume of 7.45 L at 305 K and 1.03 atm. Calculate the ma
-BARSIC- [3]

Answer:

Mass percent N₂ = 89%

Mass percent H₂ = 11%

Explanation:

First we <u>use PV=nRT to calculate n</u>, which is the total number of moles of nitrogen and hydrogen:

  • 1.03 atm * 7.45 L = n * 0.082 atm·L·mol⁻¹·K⁻¹ * 305 K
  • n = 0.307 mol

So now we know that

  • MolH₂ + MolN₂ = 0.307 mol

and

  • MolH₂ * 2 g/mol + MolN₂ * 28 g/mol = 3.49 g

So we have a <u>system of two equations and two unknowns</u>. We use algebra to solve it:

Express MolH₂ in terms of MolN₂:

  • MolH₂ + MolN₂ = 0.307 mol
  • MolH₂ = 0.307 - MolN₂

Replace that value in the second equation:

  • MolH₂ * 2 g/mol + MolN₂ * 28 g/mol = 3.49
  • (0.307-MolN₂) * 2 + MolN₂ * 28 = 3.49
  • 0.614 - 2MolN₂ + 28molN₂ = 3.49
  • 0.614 + 26MolN₂ = 3.49
  • MolN₂ = 0.111 mol

Now we calculate MolH₂:

  • MolH₂ + MolN₂ = 0.307 mol
  • MolH₂ + 0.111 = 0.307
  • MolH₂ = 0.196 mol

Finally, we convert each of those mol numbers to mass, to <u>calculate the mass percent</u>:

  • N₂ ⇒ 0.111 mol * 28 g/mol = 3.108 g N₂
  • H₂ ⇒ 0.196 mol * 2 g/mol = 0.392 g H₂

Mass % N₂ = 3.108/3.49 * 100% = 89.05% ≅ 89%

Mass % H₂ = 0.392/3.49 * 100% = 11.15% ≅ 11%

5 0
3 years ago
Which subatomic particles are located in MOST of the space within an atom?
mote1985 [20]
The answer is particels of nuclis
5 0
3 years ago
Balance this equation Hgo —&gt; Hg + O2
Nesterboy [21]

Answer:

2Hgo —>2Hg + O2

Explanation:

6 0
2 years ago
Magnesium reacts with a certain element to form a compound with the general formula MgX. What would the most likely formula be f
ziro4ka [17]

Answer:K2X

Explanation: Valency can be defined as the combining power of an element. It is the valency that dictates the value an element will have when writing a chemical formula for its compound.

MgX is a compound of magnesium and an element X. The valency of magnesium in most of its compound is +2. Now for the 2 to have been absent in the chemical formula, this shows that the element X itself have a valency if -2 for the valencies of both to have canceled out.

Now considering the element potassium, it is an alkaline metal belonging to group 1 of the periodic table. Hence, it is expected that it has a valency of +1

Forming a compound with element X means there would be an exchange of valencies between the two. We have established that x has a valency of -2. The formula of the compound thus formed by exchanging the valencies of both element would be K2X

7 0
2 years ago
Read 2 more answers
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