Month: February 2017

Application Exercises 22/02/2017

 

Question 1

While Hiking, water can be purified in the following ways:

Method Effectiveness Cost
 

 

Boiling

 Sterilizes by disease-causing micro-organisms, but does not remove impurities

 

May provide activation energy for toxic reactions to occur

 High fuel consumption

 

Bring to a boil and continue boiling for at least 1 minute
 

 

Filtration

 Filters away most micro-bacteria, sediments, and water parasites

 

With activated charcoal filters, able to filter out even more organic compounds, toxic substances, and chemical contaminants

 Expensive

 

Commercially available, but not common

 

 
 

 

 

Iodine Tablets

 Kills many common pathogens present in fresh water, but does not remove sediments or chemical pollutants

 

Leaves unpleasant aftertaste that can be reduced with Vitamin C tablets

 Cheap

 

Commercially available, available at many pharmacies

 

Waiting time of at least 30 mins before consumption

Question 2

Desalination techniques are not used more widely to produce potable water because its uses a lot of energy to produce potable drinking water therefore its is not economical and not effective.

Question 3

3a) Major source of lead in water could be from the corrosion of pipes leading to leaching of lead into the water supply

3b) Research activities done in the chemistry lab should not be accounted for the elevated lead levels in water as any waste made in the lab would have been properly disposed. Furthermore, chemical waste are not allowed to be disposed into the sink.

Question 4

I would expect water soluble vitamins to be polar compounds and fat soluble vitamins to be non polar compounds.

Polar compounds can form permanent dipole- permanent dipole interactions with water or if H in the vitamin is bonded to F,O or N, hydrogen bonds can be formed with water.

Non polar compounds can only form induced dipole- induced dipole interaction (London dispersion forces) with other molecules and so they dissolve in fat which has the same type of intermolecular forces.

In short, “like dissolves like” and molecules that can form the same types of bonds are more soluble in one another. E.g Hydrogen bond with another type of molecule that form Hydrogen bonds.

Application Exercises 15/02/2017

Image result for co2

Question 1.

Although the amount of energy leaving Earth’s surface is more than the solar energy striking the surface, Earth does not cool rapidly because greenhouse gases in the atmosphere trap and return some of the radiation. Greenhouse gases like CO2 and H2O can absorb infrared radiation to vibrate their bonds and subsequently re-emit this radiation in all directions. Some of this radiation goes back to the surface or other greenhouse gas molecules, preventing energy from escaping into space and keeping the Earth warm. Without greenhouse gases, Earth would cool rapidly to temperatures below 0 degrees Celsius.

Question 2.
The picture shows 2 men up to their chest in snow saying “This winter has lowered my concerns about global warming…” However, having a low temperature does not indicate the absence of global warming. In fact, as global warming intensifies, higher temperatures are affecting precipitation levels. This means that higher temperatures allow for more moisture to collect in the air in the form of water vapor. This increased water vapor will return to earth as part of the water cycle in the form of snow or rain, which will result in drastic changes in weather patterns and higher occurrences of severe snowstorms or floods. Therefore, the increased volume of snow should be a cause for concern instead of disregarding the presence of global warming.

Question 3.

High humidity can be present in the air. When the radio-waves travel through the air , energy is lost when the waves hit and rotate the water molecules.

In order to achieve successful transmission over long ranges, extreme amounts of energy would be needed to compensate for the loss therefore the microwave radar devices were not successful.

Question 4.

In the short run, air quality will be a serious problem.When the air quality worsens, it will affect our daily activities. It can also lead to possible health problems like breathing problems or lung diseases especially to those who suffer from respiratory problems or to kids and the elderly people.
In the long run, global warming will pose a serious problem.Global warming has caused the increase in sea levels, warmer temperatures, melting of polar ice caps and also causing extreme weather events such as hurricanes,typhoons and droughts. All these factors will affect the way of living for most people and it will be hard to recover them to its original state.

Application Exercises 08/02/2017

Image result for explosion

  1. a) Exothermic. Heat is released in process, feels hot when near
    b) Endothermic. Heat is taken in for water to transition from liquid to gas. Feels cool
    c) Endothermic. Heat is taken in for ice to transition from solid to liquid. Feels cold
  2. Reactants need weak bond strength, while products need strong bond strength
  3. Heat is a form of energy, while temperature is a quantitative measurement of that energy.
    eg. Heat refers to the energy produced in a hot oven.
    Temperature is the numerical reading of that energy (200 degrees celcius)
  4. a) Octane rating of 98 indicates a knocking characteristic of 98% isooctane and 2% heptane
    b) It does not contain enough information to determine if the fuel contains oxygens