3. Sodium carbonate, Na₂CO3 can be found in pure form and it can be used to standardize acid solutions. What is the molarity of an HCI solution if 28.3 mL of the solution is required to react with 0.256 g of Na2CO3. Calculate the volume of the gas produced at STP. [Given relative molecular mass, Mr of Na₂CO3 = 106.01, HCI = 36.46, CO₂ = 44.01 g/mol] [An M 0.0511 dm³]
Ideal and Real Gases
Ideal gases obey conditions of the general gas laws under all states of pressure and temperature. Ideal gases are also named perfect gases. The attributes of ideal gases are as follows,
Gas Laws
Gas laws describe the ways in which volume, temperature, pressure, and other conditions correlate when matter is in a gaseous state. The very first observations about the physical properties of gases was made by Robert Boyle in 1662. Later discoveries were made by Charles, Gay-Lussac, Avogadro, and others. Eventually, these observations were combined to produce the ideal gas law.
Gaseous State
It is well known that matter exists in different forms in our surroundings. There are five known states of matter, such as solids, gases, liquids, plasma and Bose-Einstein condensate. The last two are known newly in the recent days. Thus, the detailed forms of matter studied are solids, gases and liquids. The best example of a substance that is present in different states is water. It is solid ice, gaseous vapor or steam and liquid water depending on the temperature and pressure conditions. This is due to the difference in the intermolecular forces and distances. The occurrence of three different phases is due to the difference in the two major forces, the force which tends to tightly hold molecules i.e., forces of attraction and the disruptive forces obtained from the thermal energy of molecules.
only question 3 complete
![3. Sodium carbonate, Na₂CO3 can be found in pure form and it can be used to
standardize acid solutions. What is the molarity of an HCI solution if 28.3 mL
of the solution is required to react with 0.256 g of Na2CO3. Calculate the
volume of the gas produced at STP. [Given relative molecular mass, Mr of
Na2CO3 = 106.01, HCI = 36.46, CO₂ = 44.01 g/mol]
[Ans: 0.171 M, 0.0541 dm³]
4. A sample of a copper ore with a mass of 0.4875 g was dissolved in acid. A
solution of potassium iodide was added, which cause the reaction
2Cu²+ (aq) + 51-(aq) → 13(aq) + 2Cul(s)
The 13 that formed reacted with exactly 30.06 mL of 0.0210 M Na2S2O3
according to the following equation.
13(aq) + 2S2O3²-(aq) → 31-(aq) + S406²-(aq)
[Relative atomic mass, ArCu =63.55, 1 = 126.9, Na =23.00, S = 32.06, O =
16.00 g/mol]
a) Calculate the percentage by mass of copper in ore
b) If the ore contained CUCO3, determine the percentage by mass of CUCO3
in the ore.
[Ans: a) 8.23%, b) 16.0 %]
5. A sample of a MgBr2 with a mass of z g is dissolved in an excess of
concentrated sulfuric acid to produce MgSO4 and HBr gas.
MgBr2(s) + H₂SO4(aq) → MgSO4(aq) + 2HBr(g)
All HBr gas liberated is further oxidized by conc. H₂SO4 and produces Br2 and
SO₂ gas at room temperature and pressure along with water.
2HBr(g) + H₂SO4(aq) → Br2(g) + SO2(g) + 2H2O(1)
If the total volume of gas collected is 200 mL, determine the value of z.
[Ans: 0.768 g]
6. To determine the amount of dissolved oxygen in water sample, series of redox
reactions are carried out.
Reaction 1: 2Mn²+ (aq) + O₂(g) + 40H (a) → 2MnO₂(s) + 2H₂O(1)
Reaction 2: MnO2(s) + 2H(aq) + 4H+ (aq) → Mn²+ (aq) + 12(aq) + 2H₂O(l)
Reaction 3: 1₂(aq) + 2S2O3(aq) → S406²(aq) + 2H(aq)
If a 25.0 cm³ of water sample required 15.70 cm³ of a 0.00100 M Na2S2O3
solution to react with iodine liberated from the redox reaction, determine the
mass of dissolved oxygen in this sample.
[Ans: 1.256 x 10* gl](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F99035a01-21cc-457e-aa7b-608d8c373f3f%2Fa7f9b0d0-55eb-41ea-b545-fa90aac1b6bb%2Fvyvlxao_processed.jpeg&w=3840&q=75)
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