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Problem solving And Unit Conversions

Enhance your problem-solving skills and learn unit conversions with step-by-step guidance and conversion factors. Master temperature and density calculations effortlessly.

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Problem solving And Unit Conversions

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  1. Problem solving And Unit Conversions

  2. Problem Solving • One of the most important things we do in life is solve problems. • The more creative we are at solving problems, the more successful we will be. • It is helpful to use the following steps when solving a problem.

  3. Where Do We Want To Go? • To solve a problem, we need to be able to state the problem clearly. • What Do We Know? • This represents the starting point. • How Do We Get There? • How do we use the facts we know and the understanding we have of the relevant concepts to proceed from the starting point to the eventual goal – the solution to the problem.

  4. Does It Make Sense? • After we have reached the solution, we need to evaluate it. Is the answer we have obtained reasonable? • Converting Units of Measurement • This is something you encounter all the time: converting from one unit of measurement to another. • Where Do We Want To Go? • 2 dozen doughnuts = $?

  5. What Do We Know? • 1 dozen = 12 • 1 doughnut =$0.50 • How Do We Get There? • Convert dozens of doughnuts to numbers of doughnuts then to cost of doughnuts: • 2 dozen doughnuts → numbers of doughnuts →cost of doughnuts

  6. We can make each of these conversions as follows: • The doughnuts will cost $12. • Does It Make Sense? • The answer $12 seems reasonable. First, the units are correct and each doughnut costs less than $1 so we should have an answer less than $24.

  7. Conversion Factors • Ratio derived from the equality between two • different units that can be used to convert from • one unit to another. • Example: 4 quarts in 1 gallon = or

  8. Which conversion factor should be used to convert from gallons to quarts? or Let’s convert 0.75 gallons to quarts. 4 quarts 3.0 quarts x = 0.75 gallons 1 gallon

  9. Dimensional Analysis • Changing from one unit to another via conversion factors (based on the equivalence statements between the units) is often called dimensional analysis. • We will use this method throughout our study of chemistry.

  10. Temperature Conversions • Three scales: Fahrenheit scale, Celsius scale, and Kelvin scale. • Fahrenheit scale: water boils at 212oF and freezes at 32oF and normal body temperature is 98.6oF. Used widely in the US and Great Britain. Named after Daniel Gabriel Fahrenheit.

  11. Celsius scale: water boils at 100oC and freezes at 0oC. • On both the Celsius and Fahrenheit scales, the unit of temperature is called a degree, and the symbol for it is followed by the capital letter representing the scale. Named after Anders Celsius. OF and oC

  12. Kelvin scale: water freezes at 273 K and boils at 373 K. The unit of temperature is called a kelvin and is symbolized by K. Named after William Thomson, who received the title, Lord Kelvin. • The size of each temperature unit (each degree) is the same for the Celsius and Kelvin scales. • The Fahrenheit degree is smaller than the Celsius degree and the Fahrenheit unit. • The zero points are different on all three scales.

  13. Converting Between the Kelvin and Celsius Scales TCelsius + 273 = TKelvin Converting Between the Fahrenheit and Celsius Scales

  14. Density is a characteristic physical property of • a substance and can be used for identification. • Density is the ratio of mass to volume, or mass • divided by volume (D = m/v). • The SI unit for density is kg/m3. In the lab you • will usually see density expressed as g/mL or • g/cm3.

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