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Homework Help Forum: Chemistry
Current Questions | Post a New Question | Answer this Question | Further Reading

Posted by Jared on Sunday, July 8, 2007 at 1:13am.
What is the pH of the solution created by combining 2.50 mL of the 0.10 M NaOH(aq) with 8.00 mL of the 0.10 M HCl(aq)?

I believe if my calculations are correct the answer is 1.28

however i do not know how to answer this question because it has a weak acid instead of a strong acid

What is the pH of the solution created by combining 2.50 mL of the 0.10 M NaOH(aq) with 8.00 mL of the 0.10 M HC2H3O2(aq)?

Yes, the 1.28 pH for the first one is correct.
The second one forms a buffer. write the equation.
NaOH + HC2H3O2 ==> NaC2H3O2 + HOH

Calculate mol NaOH initially.
Calculate mols HC2H3O2 initially.
There will be an excess of HC2H3O2 and there will be some NaC2H3O2 formed.
Then use the Henderson-Hasselbalch equation to caluclate the pH of the buffer created. Post your work if you get stuck.

What is a variable?
What is the definition of model?
Why are models useful in chemistry?

## To answer the first question, "What is a variable?" in the context of chemistry, a variable is a factor or quantity that can change in an experiment or equation. In other words, it is a symbol or letter used to represent an unknown value or a value that can vary.

To find the definition of a variable or any other term, you can either search online or refer to a chemistry textbook or reference book. These resources will provide detailed explanations and examples to help you understand the concept.

Now, let's move on to the second question, "What is the definition of a model?" In chemistry, a model is a simplified representation or explanation of a chemical phenomenon or process. It is often used to make predictions, visualize complex concepts, or simplify calculations. Models can be physical, such as molecular models, or they can be mathematical equations or diagrams.

To find the definition of a model or any other term, you can search online or refer to a chemistry textbook or reference book. These resources will provide detailed explanations and examples to help you understand the concept.

Lastly, the third question asks, "Why are models useful in chemistry?" Models are useful in chemistry for several reasons. Here are a few:

1. Visualizing complex concepts: Chemistry deals with tiny particles such as atoms, molecules, and ions, which are not visible to the naked eye. Models, such as molecular models, allow chemists to visualize and understand the structure and behavior of these particles, making it easier to understand and explain chemical phenomena.

2. Simplifying calculations: Mathematical models, such as equations and formulas, allow chemists to simplify complex calculations. For example, the ideal gas law is a mathematical model that describes the behavior of gases, making it easier to predict and calculate variables such as pressure, volume, and temperature.

3. Making predictions: Models can help chemists make predictions about the behavior of chemicals or the outcomes of reactions. By using models based on previous experimental data and theoretical principles, chemists can estimate properties, reactions, and potential outcomes, which can guide further research and experimentation.

It is important to note that models are simplified representations of reality and may not always perfectly represent all aspects of a chemical system. However, they provide a useful framework for understanding and explaining chemical phenomena.