science labs2 – exclusivewritings.com
Lab 1 Comparing Vinegar with a Chemical Based Supermarket Cleaner
Great things are done by a series of small things brought together.
~ Vincent Van Gogh
As wonderful as technology has been in enhancing our lives and creating longevity, it’s also been a double-edged sword. Human activity and the constant drive to expand has come at the expense of the global environment. Greenhouse gases are contributing to global climate warming as emissions caused by human activity continue to increase. The depletion of the ozone layer, essentially the protector of life on earth, has never been greater. Chemical agents sprayed into the atmosphere rise-upward and take their toll on the ozone and our environment. Empty containers often end up in landfills indefinitely. We need to do our part and take action now through use of natural and biodegradable products.
- Diluted vinegar (half vinegar with half water)
- Supermarket cleaning product that is safe on glass (such as Windex)
- Cleaning cloth
- Old newspaper
1. Find a dirty window (glass pane). It should be a surface that is visibly dirty all-around.
2. Scrunch up your newspaper and pour some vinegar on it. The paper should be saturated, but only so it’s partially wet with vinegar (enough to clean the surface). Scrub one-half of the window/mirror for about a minute, making sure to scrub in a swooping circular motion.
3. On the second-half of the window, spray your supermarket cleaning agent. Take your cleaning cloth and clean the second-half of the window for a minute, using the same swooping circular hand motion.
4. When you’re done, observe the window / mirror. Which half is cleaner? Is there a noticeable difference?
Answer the following questions:
1. Which method of cleaning the window do you think is the most environmentally friendly?
2. Was there enough of a different between the chemical cleaning agent and the vinegar to justify its use and its potential negative effects on the environment?
With an eye on the environment (and the consumer pocket-book), many big-name companies are starting to jump on the “natural” bandwagon. You’ll find more natural-based cleaners these days than in the past, but be weary of labels! Some companies use clever marketing gimmicks to make their products appear to be “natural”, when in fact they are not. A common ploy is to label a bottle with “natural orange/lemon scent”. When a consumer glances at the product they see “natural” and assume the cleaner is natural. Always check the listed ingredients to see if the product youâ€™re purchasing is truly made of natural ingredients.
Many supermarket cleaners contain harsh chemicals that are dangerous to the environment and atmosphere. Vinegar is a non-toxic acidic liquid that can clean just as effectively as many chemical based agents, without the damaging side-effects. The newspaper was used to demonstrate how recycled material can make a viable substitute for cleaning clothes, which requires a lot of energy to produce.
Lab 2 Changes in Sea Level
But we have only begun to love the earth. We have only begun to imagine the fullness of life.
How could we tire of hope?–so much is in bud.
~ Denise Levertov
Sea level continually changes in response to numerous factors, including glacial melting, tectonic forces, and climatic changes. Currently, sea level is rising at a rate of 1.5 to 3.9 mm/year. Studies by the U.S. Environmental Protection Agency and other organizations indicate that global warming may be linked to increases in sea level. Global warming is a worldwide rise in surface temperatures. Scientists hypothesize that global warming is caused by human activities, such as the burning of fossil fuels. Even a small rise in global temperatures can melt glaciers and make seawater expand, both of which increase the volume of water in the oceans.
In this lab we will be analyzing how have coastlines and sea level changed during geologic time?
Our major objectives for the lab would be:
â€¢ Observe and measure changes in coastlines.
â€¢ Describe changes in sea level over geologic time.
â€¢ Predict the impact of rising sea level on coastal regions.
1. Take a few minutes to study the sea-level map on the next page. Note the map scale. You will use the map and the map scale to answer the questions in this lab.
2. Use the string to measure distances along the coast or between two points that are not in a straight line. For example, you can lay the string along the coast so that it follows the outline of the coast, then measure the distance by laying the string along a ruler.
Answer the questions that follow:
1. How does the landward limit of the coastline 5 million years ago compare to its current location? How does it compare to the location of the coastline 20 000 years ago?
2. Locate South Carolina on the map. How far did its coastline extend into the Atlantic Ocean 20 000 years ago? How far inland was its coastline 5 million years ago?
3. Measure and record the entire length of the current coastline and its length 20 000 years ago. Describe how it has changed. What caused these changes?
4. Use the map to describe how sea level has changed in the last 20,000 years. Why do you think these changes occurred?
1. The last ice age peaked roughly 10 000 years ago. Since then, sea level has risen approximately 130 m. Describe the effect of small rises in sea level on coastal areas.
2. The mass of huge glaciers exerts pressure on underlying land and causes it to sink. When these glaciers retreat, the land that they covered often rises, or rebounds. Where on the map would you expect glacial rebound to be occurring? How might this rebound affect the levels of seas and other large bodies of water?
3. Global sea level could rise by 30 cm within the next 70 years. Predict which areas on the map would be affected most. Explain your answer.
4. Discuss the potential impacts of rising sea level on low-lying coastal areas.
Lab 3 Acid Rain and Counteracting its Detrimental Effects
In the end, we will conserve only what we love. We will love only what we understand. We will understand only what we are taught.
~ Baba Dioum
Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions (low pH). Aqueous solutions are termed to be acidic if the pH is less than 7.00 and caustic (alkaline) if the pH is greater than 7.00. A pH of 7.00 is neither acidic nor caustic.Each pH unit change represents a 10 times change in the acidic/caustic character of the solution. Universal pH paper is commonly used to determine the pH of a number of aqueous solutions.
pH of some common solutions
Acid rain can have harmful effects on plants, aquatic animals, and infrastructure. Acid rain is caused by anthropogenic emissions of sulfur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids. Governments have made efforts since the 1970s to reduce the release of sulfur dioxide into the atmosphere with positive results. The chemicals in acid rain can cause paint to peel, corrosion of steel structures such as bridges, and erosion of stone statues. The lower pH concentrations in surface water that occur as a result of acid rain can cause damage to fish and other aquatic animals. At pHs lower than 5 most fish eggs will not hatch and lower pHs can kill adult fish. As lakes and rivers become more acidic, biodiversity is reduced. Acid rain has eliminated insect life and some fish species, including the brook trout in some lakes, streams, and creeks in geographically sensitive areas, such as the Adirondack Mountains of the United States. Soil biology and chemistry can be seriously damaged by acid rain. Some microbes are unable to tolerate changes to low pH and are killed. Other plants can also be damaged by acid rain, but the effect on food crops is minimized by the application of lime and fertilizers to replace lost nutrients. In cultivated areas, limestone may also be added to increase the ability of the soil to keep the pH stable, but this tactic is largely unusable in the case of wilderness lands. When calcium is leached from the needles of red spruce, these trees become less cold tolerant and exhibit winter injury and even death.
In this lab we will see how a simple acid in lemon juice (citric acid) can be somewhat neutralized by baking soda (sodium bicarbonate).
The reaction between baking soda and lemon juice is an acid-base reaction, because it involves an acid (citric acid in the lemon juice) reacting with a base (sodium bicarbonate, more commonly known as baking soda). We can write this reaction as follows:
C6H8O7 + 3NaHCO3 <—> Na3C6H5O7 + 3H2CO3
In words, a molecule of citric acid reacts with three molecules of sodium bicarbonate to form a molecule of sodium citrate and three molecules of carbonic acid. Although an acid is reacting with a base, this is not a neutralization reaction. In a neutralization reaction, the products are water and a salt; our products, however, are a weaker acid and an organic salt. If you were to measure the pH of a solution containing the products, it would be lower than 7 (acidic).
On the left side of the equation, citric acid is the acid and sodium bicarbonate is the base; on the right side, carbonic acid is the acid, and sodium citrate is the base. The forward reaction is favored because citric acid is a stronger acid than carbonic acid (or, alternately, because sodium bicarbonate is a stronger base than sodium citrate). However, the difference is not very significant, and hence it is indicated with the double-headed arrows that both the forward and reverse reactions will occur, leading to an equilibrium.
This is not the whole story, however. The carbonic acid formed in the above reaction dissociates rapidly to form carbon dioxide and water:
H2CO3(aq) —> CO2(g) + H2O(l)
When this happens, you will notice the solution bubbling and foaming rapidly.
- Lemon juice bottle from the grocery store
- Baking soda
- Measuring cups and spoons
- Spoon for stirring
- Universal pH paper or pH testing strips (available at a hardware store or store that sells pool and aquarium supplies)
- Eye Droppers or Glass droppers or Plastic droppers
1. Measure 2 tablespoons of lemon juice. Transfer it to a large cup or container and dilute with 5 tablespoons of water rinsing any lemon juice from the spoon
2. Using universal pH paper measure the pH of the lemon juice solution.
3. Add 1 tablespoon of baking soda in another cup.
4. To the second cup with baking soda, add 5 tablespoons of water and stir with a spoon.
5. Using universal pH paper measure the pH of the baking soda solution.
6. Add one dropper full of the baking soda solution to the lemon juice solution, stir and note the pH.
7. Keep repeating until the pH is close to neutral. Remember it will still yield an acidic solution.
8. Measure how much of the baking soda solution remained in the beaker and calculate how much was used up.
9. Write a detailed lab report explaining your experiment and results. Use the template on how to write a lab report from your second lab.