Chemistry Answers

6. Suppose that you are travelling in the Space Shuttle Endeavor on a journey to Mars. The atmosphere (of the vehicle) consists of 20% oxygen and 80% helium by volume. It was noticed before take off from the Kennedy Space Center that there is a small leakage which if unchecked, would lead to a continual loss of gas at a rate of 0.05 atm/day through effusion. If the temperature in the space shuttle is maintained at 22oC and the volume of the vehicle is 15,000 liters. Calculate the amounts of helium and oxygen in grams that must be stored on a 5-day journey to allow for the leakage.

A reversible reaction of methanol (M) dehydrogenation to formaldehyde (F) and hydrogen (H):

CH₃OH ⇄ CH₂O + H₂

is characterized by an equilibrium constant K_C = 10 at a temperature t = 670°C. Given the following values of standard molar entropies:

S^⦵_M = 239,9 J/(mol·K)

S^⦵_F = 218,9 J/(mol·K)

S^⦵_H = 130,7 J/(mol·K)

Calculate the value of standard enthalpy of this reaction (∆H^⦵_R)

Universal gas constant R = 8,314 J/(mol·K)

1.    A sample of material weighing m = 3.400 g was incinerated inside a bomb calorimeter. The calorimeter was charged with m_W = 1500 g of water. The initial temperature of the calorimeter was t₀ = 24.223°C. After the incineration the temperature rose to t₁ = 29.654°C.

Calculate the heat of combustion of 1 kg of tested material.

Heat capacity of the calorimeter: c_P,(c) = 3.3 kJ/K

Specific heat of water: C_P,(W) = 4.18 kJ/(kg·K)

1.     A first-order reaction reaches a conversion equal to X₁ = 0.75 in τ₁ = 10 minutes. Calculate the time τ₂ required to reach conversion X₂ = 0.9

What is the mass of technical calcium carbide with a mass fraction of 12% required for the production of acetylene with a volume of 6.72 l (nu)?

1)     What is the mass of water if it contains 5 moles of hydrogen atoms?                              

2)      Aspirin is a compound with the molecular formula C₉H₈O₄. What is its percent composition?

3)     A 24.81-g sample of a gaseous compound containing only carbon, oxygen, and chlorine is determined to contain 3.01 g C, 4.00 g O, and 17.81 g Cl. What is this compound’s percent composition?

What is the mass of water if it contains 6.022 x 10²⁵ atoms of oxygen

How many grams of Lactic acid (C6H10O5) should be dissolved in 647g of cyclohexane (C6H12) to raise the boiling point to 84.910C? The normal boiling point of cyclohexane is 810C and its molal boiling point is 2.75 0C/m.

using conversion method, calculate the molality and molarity of aqueous phosphoric acid solution 1.88 gram/ml containing 20% by mass of h3 po4? h=1 p=31,o=16

A solution prepared by adding 10g of an unknown non-volatile, non-electrolyte solute to 100 g of water. The Boiling point of the solution is elevated by 0.433 0C above the normal boiling point of the solvent. What is the molar mass of the unknown substance?