General Chemistry Answers

5). Solve the following problem, giving answers with the correct number of decimal places.

1.08 dm³ - 0.585 dm³

7). The pH scale is the most common logarithmic scale you will encounter on the course. The pH of a solution is defined as the negative logarithum₁₀ of the concentration of hydrogen ions:

pH = -log₁₀ [H⁺ (aq) ] 

The hydrogen ion concentration can be determined by taking the antilog of the negative pH value

[H⁺ (aq) ] = 10^-pH 

 What is the concentration of aqueous hydrogen ions in a solution of pH 6.7?

8).  The combined gas equation is given below;

 Rearrange the equation making V₁ the subject of the equation.

1)    The theoretical maximum yield of MgCl₂ that could be formed from 5.00g Mg in the reaction,

Mg (s)+2HCl (aq)→MgCl₂ (aq)+H₂ (g)

is 19.6g. In a laboratory experiment, a student, was able to make 14.2g. What was the percentage yield?

2). A pressure of 101,325 Nm^-2 is equivalent to 1.00 atmospheres. Convert a pressure of 0.65 atmospheres to newton per metre squared (Nm^-2), giving your answer to 3 significant figures.

3). The relationship between concentration, amount of material (number of moles) and volume is,

Concentration (mol dm^-3)   =  moles (mol) / volume (dm³)

A solution contains 1.5 x 10^-2 mol of sodium hydroxide (NaOH) dissolved in 75.0 cm³ of water. What is the concentration of the sodium hydroxide solution?

4). The speed of light in a vacuum is 299,792,500 ms^-1. Convert to standard form and give the value to 3 significant figures.

Write the equations for oxidation, reduction and overall reaction for the following electrochemical cell: Cu(s)/Cu2+ (aq) // Fe 3+ (aq)/ Fe2+ (aq) / Pt (s)

Balanced the following redox equations. All occur in acid solution. a) Zn (s) + NO3 - (aq) Zn2+ (aq) + N2O (g) b) Ag (s) + NO3 - (aq) Ag+ (aq) + NO2 (g)

Question text

Consider the following: KClO₃ (122.55 g/mol), is prepared from KCl (74.55 g/mol) and O₂ gas (32.00 g/mol) by the following process:        

KCl   +  O₂  ------------->  KClO₃   (unbalanced reaction)

The amount of oxygen gas in grams that will be needed to produce 14.2 mL of KClO₃ (ρ = 2.34 g/mL) is

A sample of air contains 78.08% Nitrogen, 20.94% oxygen and 0.980% Argon, by volume. How many moles of oxygen are present in 1.00L of the sample at 25.0 ^oC at 1.00 atm?

Note: if your answer is in exponential form just like this: 5.555 x 10^-7, 

express your answer in this form: 5.555E-7

Determine the empirical formula of the given polymer: 59.90% C, 8.06% H and 32.0% O. The molar mass of the polymer is 500.0 g/mol

Note: if for example your answer is C₁₀H₁₂O₁₆, write it in this form C10H12O16 . Don't put space.

A sample of nitrogen gas is bubbled through water at 298K and the volume collected is 250.00 mL. The total pressure of the gas, which is saturated with water vapour is found to be at 98.8 kPa at 298 K. What amount in mole of nitrogen is in the sample? The vapour pressure of water at 298K is 3.17 kPa. (R = 0.08206 L.atm/mol.K)

Note: if your answer is in exponential form just like this: 5.99 x 10^-2 , express your answer in this form: 5.99E-2

6.407 g of solid CO₂ (44.01 g/mol) is put in an empty sealed 3.45 x 10³ mL container at a temperature of 305.7-K. When all the solid CO₂ becomes gas, what will be the pressure (in bar) in the container? ( R = 0.08206 L.atm/mol.K)

A mixture of hydrogen gas and oxygen gas exerts a total pressure of 3.456 atm on the walls of its container. If the Hydrogen gas has a mole fraction of 0.667, find the partial pressure of the oxygen gas.