HELLO! :D

My best three posts are:

• http://rose-science-blog.blogspot.com/2011/03/chemical-changes.html
• http://rose-science-blog.blogspot.com/2011/03/acids-and-alkalis.html
• http://rose-science-blog.blogspot.com/2011/04/osmosis-part-of-diffusion.html

Thanks!

Osmosis a Part of Diffusion?

Headline: Osmosis a Part of Diffusion?

Today, we went through Diffusion and Osmosis which is under the topic, Transport in Living Things. People usually think that osmosis and diffusion work in the same way. Actually, osmosis and diffusion are different from one another. Osmosis is a type of diffusion.

I learnt that diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. As for osmosis, it is the net movement of water molecules from a region of higher concentration of water molecules to a region of lower concentration of water molecules through a partially-permeable membrane.

The 3 differences between osmosis and diffusion are:

1. Diffusion can occur in solid, liquid or gaseous state but osmosis can only occur in the liquid state.

• Diffusion in solid (e.g. copper (II) sulfate crystals being embedded on colourless agar)
• Diffusion in liquid (e.g. crystals of potassium permanganate diffuse in liquid)
• Diffusion in gas (e.g. the scent of perfume in the air)

2. Diffusion is able to take place with/without a partially-permeable membrane but osmosis can only take place with a partially-permeable membrane.

• In some cases, both big and small molecules are able to pass through the partially-permeable membrane in diffusion.
• Only small water molecules are able to pass through the partially-permeable membrane in osmosis.

3. Diffusion involves movement of any molecules while osmosis involves movement of water molecules only.

I also learnt that both osmosis and diffusion occur in living organisms. For instance, diffusion of gases can happen in both plants and animals. In addition, diffusion of digested food into the bloodstream from the small intestine also occurs in animals. As for osmosis, it occurs in both plants and animals cells. The membranes in the cells are partially permeable.

When the concentration of water molecules outside the cells are lower than the water molecules in the cells, the water in the cells will leave through osmosis and causes the plant cells to turn flaccid and causes the animals cells to shrivel up. As for when the water molecules outside the cells are higher than the water molecules in the cells, the water will go in the cells by osmosis and causes the plant cells to turn flaccid and causes the animal cells to swell and burst.

(Example of plant cells undergoing osmosis)



Sources: Google Images

Continuation of Acids and Alkali Worksheet

Headline: Continuation of Acids and Alkali Worksheet.

In today's Science lesson, we went through the worksheet on acids and alkalis which we had gone through part of it yesterday.

I learnt that:

• In car engines, it is very unlikely for the measurement of pH to be done
• The acid in car battery is very acidic, which have a pH of 1
• Distilled water is neutral with a pH of 7
• The alkali in potassium hydroxide is very alkaline as it has a pH of 13
• When the universal indicator is added to an acid, the colour of it will first be green, then change to yellow, then orange and then red
• As for when the universal indicator is added to a very strong alkali, with a pH of 14, it will turn violet in colour

(Universal indicator with an alkali of pH 13)

(Universal Indicator)



Sources: Google Images

Acids and Alkalis Worksheet

Headline: Acids and Alkalis Worksheet.


For today's Science lesson, we went through the acids and alkalis worksheet which we had completed before this lesson.


I learnt that:

• Baking powder is known as sodium carbonate
• When you have gastric pains, acids are being produced in your body
• Calcium hydroxide is used to neutralise the acids in the water
• Ammonium is used to describe salt while ammonia is used to describe gas
• Sulfuric acid is used to remove rust from iron and steel objects in industry
• Nitric acid is used in making explosive
• Potassium hydroxide is an ingredient in paint removers
• Limewater is known as calcium hydroxide

(Baking Powder - Sodium carbonate)

Sources: Google Images

Research

In this Science lesson, we were given time to work on our Scientific Thinking Project research. For our group, we divided the tasks so that each of us has a specific work to accomplish.

I learnt that there are food, such as carrots, coals, lemons, etc., that are able to aid in the reproduction of the bacteria. Well, my task was to research on carrots and my other teammates are tasked to research on other food for the bacteria. We have to research on them so that the results of our experiments would be better and more accurate.

I also learnt that carrots are carriers for bacteria contaminants due to them being exposed during handling, packaging, etc. I also found out that E.coli, bacteria that is used in our experiment, can contaminate a fresh and preserved product which in turn can cause us to have illnesses.

(Carrots)



Sources: Google Images, http://www.livestrong.com/article/170387-carrots-food-poisoning/

Going Through Worksheets

In today's Science lesson, we went through worksheets which we had completed in the last few days. The worksheets were on equations of acids and alkalis and chapter 14 workbook, Changing Matter.

3 Thoughts:
1) The meaning of decomposition is known as breakdown and not combine. Examples of substances which undergo decomposition in the presence of heat are calcium carbonate, copper carbonate and sugar.
2) I learnt that producing light in a light bulb is a physical change as the filament in the light bulb is heated up, and electrical energy is converted to heat and light energy. In addition, the change is reversible and no new substances are formed.
3) In the reaction of acids and metal carbonates or reactive metals, chemical salts are always formed. We name the salts based on the types of acids and metals used at the start of the experiment. For example, when sodium and hydrochloric acid is being mixed together, the salt formed is called sodium (follows the name of the reactive metal used) chloride (known as the last name which is based on the type of acid used).

2 Questions:
1) Does decomposition occurs at a specific temperature?
2) The changing of energy from one form to another is not a chemical change right?

1 Useful application:
1) By knowing the names of the salts produce through chemical reactions, we are able to know which substances are given out in the different types of reactions.

(Few examples of the equations on the reactions of acids and reactive metals)

Sources: Google Images

Video and Worksheet

Today, Mdm Riza showed us a video on the reaction of zinc with hydrochloric acid as the experiment we had done before, by mixing both the substances had failed. The inflated balloons in the video showed us that gas is produced during the reaction. We then had to complete a worksheet based on what we saw from the video.

I learnt that when zinc (reactive metal) mixes with hydrochloric acid, they produce hydrogen gas that caused both the balloons to be inflated. But the rate at which the balloons are inflating is different from one another. I think it is because of the different amount of the zinc and hydrochloric acid in both the conical flasks. I wonder if the balloons would burst if the reaction was stronger.

I also learnt that effervescence is a process in which bubbles are continuously given off by the reaction in the liquid at a very fast rate.

(Reaction of zinc and hydrochloric acid that causes the balloons to be inflated)



 Sources: Google Images