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Chemistry is an important branch of science which mainly deals with the chemical and physical changes that occur in nature. According to chemistry, atoms are the smallest unit of any matter and involve all the chemical and physical reaction. Physical changes are associated with the change in the physical state of matter, whereas chemical changes are related to the change in chemical composition of the substances. Melting of ice is an example of physical change and burning of paper or rust on an iron nail is an example of a chemical change.

Now you can easily understand how chemistry helps us to understand the changes which we observe in our surroundings. Over and above learning of changes, chemistry also provides a mathematical explanation for thermodynamic process such as energy transfer between the system and surroundings. You must have heard about $1^{st}$, $2^{nd}$ or zeroth laws of thermodynamics. We can easily apply these laws on physical and chemical process and can determine the energy change.

The numerical problems of chemistry help to determine the change in energy level of substances during chemical and physical processes. All the numerical problems have a certain way to solve and practice makes you perfect in solving these problems. Let’s discuss how you can solve the mathematical problems of chemistry with the given data. If you have question you need answers for, your best bet is to take expert help from TutorVista’s respectable credential tutors. It’s always best to get a live person clarify all your chemistry doubts and gauge your progress.

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## How is Critical Thinking Used to Solve a Problem?

When a problem is complex or challenging to define we may use other, formal methods of problem solving. Scientist and healthcare researches use a precise method to investigate problems and arrive at solutions. This method is called scientific problem solving.

The seven steps of scientific problem solving are as follows:
1. Identify the problem
2. Gather information relevant to the problem.
3. Formulate tentative solutions (hypothesis) choose preferred solution.
4. Plan action to test suggested solution.
5. Experiment and observe the results.
6. Interpret the results (draw conclusion) understand what the results mean.
7. Evaluate the solution either concluding or revising the study to test the solution again if results are unsatisfactory.

The use of complicated mix of inquiry, knowledge, intuition, logic, experience and common sense is called critical thinking.

The following are the steps that should be considered when a problem is solved:
• Plan in detail as to how the problem is to be solved.
• Specify definitely what each number represents and the units in which it is expressed when the mathematical operation is carried out.
• Having solved the problem, examine the answer to see if it is reasonable and practical.
• If the problem is not understood, have it explained to you at the very earliest possible time.

## Mastering Chemistry Help

Most of Chemistry is concerned with the applications of concepts to practical problems. Consider the example below:

### Example:

When 2.53 grams of metallic mercury is heated in air, which produces 2.73 grams of a red orange residue. Assume that the chemical change is the reaction of the metal with oxygen in air

Mercury + oxygen red-orange residue

What is the mass of oxygen that reacts? When the red - orange residue is heated, it decomposes to give back the mercury and release the oxygen when it is collected. What is the mass of collected oxygen?

### Problem strategy

Apply the law of conservation of mass to the reaction.According to this law, the total mass remains constant during a chemical reaction; that is

mass of substance before reaction = mass of substance after reaction
Solution:

From the law of conservation of mass

Mass of mercury + mass of oxygen = mass of red-orange residue

Substituting the values
2.53 grams + mass of oxygen = 2.73 grams

or

mass of oxygen = (2.73 - 2.53)grams
= 0.20grams

The mass of oxygen collected when the red - orange residue decomposes equals the mass of oxygen that originally reacted.
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