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Identifying Substances Experiment

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Introduction

Title: Identification of Unknown Substances from Physical and Chemical Properties

Prepared for: Ms. E. McDonald

Stanley Ho, Wilton Chan

SCN1D

Problem

Why I am conducting this experiment?

  I was given 5 unknown samples, which are sodium chloride, sodium thiosulfate, calcium carbonate, sodium bicarbonate and sodium nitrate and these samples are all white and solid. However, I don’t know which substance is which sample and I was only given some information about the physical and chemical properties of these substances.  In order to identify the 5 unknown samples, knowing which sample is which substance, I have to carry out this experiment, finding out the chemical and physical properties of these samples.  

How can we identify five unknown chemical samples that seem to look the same?

By doing this experiment, I can know the physical and chemical properties of these samples. After I get my results about the physical and chemical properties of these samples, I can compare my results with the information given by the past student and identify the 5 unknown samples, finding out which sample is which substance.

Hypothesis

Hypothesis for this identify:

  After I finish this experiment, I suppose I can identify the 5 samples, knowing which sample matches which substance through finding the chemical and physical properties of the samples. Also, I will know what a chemical and physical property is and I will know how to find them out.

Materials

Refer to,

...read more.

Middle

Fine

Small

Medium

Medium

Very fine

1

Particle shape

Powder

Cubic crystal

Crystal

Hexagonal crystal

Powder

2

Solubility in water

Insoluble

Soluble

Soluble

Soluble

Soluble

3

Reaction in acid

Fizzles and some dissolves

None

None

Turns yellow

Fizzles

4

Electronic conductivity

Low

High

High

High

High

Table 1. Physical and chemical properties of the 5 unknown samples.    

Identification of the 5 unknown samples

  After I’ve done experiment and compared my data table with the information given by the past student, I found out which sample is which substance. Here are the results:

  • Calcium carbonate ( Sample A )
  • Sodium chloride ( Sample B )
  • Sodium nitrate ( Sample C )
  • Sodium thiosulfate ( Sample D )
  • Sodium bicarbonate ( Sample E )

Discussion Questions

1

  1. A property is a characteristic of anything. The word “property” is especially used to describe a substance.
  2. A chemical property is a characteristic of a substance involves a chemical reaction, people require to change the substance to another substance if they want to determine a chemical property. But a physical property is a characteristic of a substance that is about the appearance of a substance, or anything that can be determined without changing that substance into another substance.
  3. Color, particle shape, particle size, electrical conductivity and solubility in water are the physical properties I’ve tested.
  4. Reaction in acid is the chemical property that I’ve tested.

2

The property “particle shape” helped me most to decide on the identity of the unknowns. Because after I found out all the particles shapes of the unknowns, at least I can identify two of the unknown samples.

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Conclusion

I found out that three of the samples are crystals. But the data table in the reference told me that only 2 of the samples are crystals. I might be wrong, as I wasn’t sure if one of the samples was crystal or not. I have different results about particle sizes after I observed from the samples, because size is a very abstract category and everyone has different point of view for the size of any object.  

Ways to Improve Experiment

  Firstly, if I want to improve my experiments, I have to learn how to use conductivity meter. Because my partner and I didn’t use the conductivity very correctly, the results about the electrical conductivity for each substance might not be correct.

  Secondly, I have to know how to describe the shape of a particle. During the experiment, I had some confusion about the particle shape of a substance. So, I need to learn that.

Application of Knowledge

  After this experiment, I am able to find the chemical and physical properties of different substances. If I find any unknown substance in the future, I would be capable to find out the chemical and physical properties of that unknown substance. I might be able to identify that unknown substance.          

...read more.

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