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4 years ago

what is the molarity of a solution of potassium dichromate (k2cr2o7) if 187 grams are dissolved in 250 ml?

1 answer:

4 0

Answer:
Molarity = 2.54 mol.L⁻¹

Solution:
Molarity is the amount of solute dissolved per unit volume of solution. It is expressed as,

Molarity = Moles / Volume of Solution ----- (1)

Data Given;
Mass = 187 g

Volume = 250 mL = 0.25 L

First calculate Moles for given mass as,

Moles = Mass / M.mass

Moles = 187 g / 294.185 g.mol⁻¹

Moles = 0.6356 mol

Now, putting value of Moles and Volume in eq. 1,

Molarity = 0.6356 mol ÷ 0.25 L

Molarity = 2.54 mol.L⁻¹

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What are the OSHA PEL-TWyA and PEL-STEL values for nitric acid?

Sedbober [7]

The OSHA limit for STEL-TWA is 2ppm and the PEL-STEL value is 4ppm to the exposure to nitric acid.

OSHA refers to Occupational Safety and Health Administration has adopted standard values for the exposure to harmful and hazardous chemicals so that the safety of workers and testing animals could be ensured.

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1 year ago

Archimedes principle states that the buoyant force on an object is equal to the blank of the fluid displaced by the object

telo118 [61]

False. The principle states that the buoyant force on an object is equal to the weight of the fluid displaced by the object.

<h3>What is Archimedes' principle?</h3>

It is a theory propounded by Archimedes. It opines that a floating body is acted upon by a buoyant force.

The buoyant force is the same as the weight of the fluid displaced by the floating body.

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2 years ago

What is the pH of a substance that has [H+] = 0.0081? 8.1 -1.09 -8.1 1.09

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3 years ago

If 175 g of phosphoric acid reacts with 150.0 g of sodium hydroxide, what is the limiting reactant? How many grams of sodium pho

Evgen [1.6K]

Answer:

NaOH is the limiting reactant.

204.9 g of sodium phosphate are formed.

51.94 g of excess reactant will remain.

Explanation:

The reaction that takes place is:

H₃PO₄ + 3NaOH → Na₃PO₄ + 3H₂O

First we convert the mass of both reactants to moles, using their respective molar masses:

H₃PO₄ ⇒ 175 g ÷ 98 g/mol = 1.78 mol

NaOH ⇒ 150 g ÷ 40 g/mol = 3.75 mol

1.78 moles of H₃PO₄ would react completely with (1.78 * 3) 5.34 moles of NaOH. There are not as many NaOH moles so NaOH is the limiting reactant.

We calculate the produced moles of Na₃PO₄ using the limiting reactant:

3.75 mol NaOH * $\frac{1molNa_3PO_4}{3molNaOH}$ = 1.25 mol Na₃PO₄

Then we convert moles into grams:

1.25 mol Na₃PO₄ * 163.94 g/mol = 204.9 g

We calculate how many H₃PO₄ moles would react with 3.75 NaOH moles:

3.75 mol NaOH * $\frac{1molH_3PO_4}{3molNaOH}$ = 1.25 mol H₃PO₄

We substract that amount from the original amount:

1.78 - 1.25 = 0.53 mol H₃PO₄

Finally we convert those remaining moles to grams:

0.53 mol H₃PO₄ * 98 g/mol = 51.94 g

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3 years ago