1 Steps in the Scientific Method 1. 1. Observations Observations quantitative quantitative qualitative qualitative 2. 2. Formulating hypotheses Formulating hypotheses possible explanation for the possible explanation for the observation observation 3. 3. Performing experiments Performing experiments gathering new information to gathering new information to decide decide whether the hypothesis is valid whether the hypothesis is valid
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1 Steps in the Scientific Method 1.Observations quantitative quantitative qualitative qualitative 2.Formulating hypotheses possible explanation for the.
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Steps in the Scientific Method
1.1. ObservationsObservations
quantitativequantitative
qualitativequalitative
2.2. Formulating hypothesesFormulating hypotheses
possible explanation for the observationpossible explanation for the observation
3.3. Performing experimentsPerforming experiments
gathering new information to decidegathering new information to decide
whether the hypothesis is validwhether the hypothesis is valid
A digit that must be A digit that must be estimatedestimated is called is called uncertainuncertain. A . A measurementmeasurement always has always has some degree of uncertainty.some degree of uncertainty.
Accuracy Accuracy refers to the agreement of a refers to the agreement of a particular value with theparticular value with the true true value.value.
PrecisionPrecision refers to the degree of agreement refers to the degree of agreement among several elements of the same among several elements of the same quantity.quantity.
Random Error Random Error (Indeterminate Error) - (Indeterminate Error) - measurement has an equal probability of measurement has an equal probability of being high or low.being high or low.
Systematic Error Systematic Error (Determinate Error) - (Determinate Error) - Occurs in the Occurs in the same directionsame direction each time (high each time (high or low), often resulting from poor technique.or low), often resulting from poor technique.
Rules for Significant Figures in Mathematical Operations
Multiplication and Division: Multiplication and Division: # sig figs in # sig figs in the result equals the number in the least the result equals the number in the least precise measurement used in the calculation.precise measurement used in the calculation.
Rules for Significant Figures in Mathematical Operations
Addition and Subtraction: Addition and Subtraction: # sig figs in the # sig figs in the result equals the number of decimal places result equals the number of decimal places in the least precise measurement.in the least precise measurement.
6.8 + 11.934 =6.8 + 11.934 =
22.4896 22.4896 22.5 (3 sig figs)22.5 (3 sig figs)
Mixtures have variable composition.Mixtures have variable composition.
AA homogeneous mixturehomogeneous mixture is a solution (for is a solution (for example, vinegar)example, vinegar)
AA heterogeneous mixtureheterogeneous mixture is, to the naked is, to the naked eye, clearly not uniform (for example, a eye, clearly not uniform (for example, a bottle of ranch dressing)bottle of ranch dressing)
Element:Element: A substance that cannot be A substance that cannot be decomposed into simpler substances by decomposed into simpler substances by chemical means.chemical means.
Compound:Compound: A substance with a A substance with a constant composition that can be constant composition that can be broken down into elements by broken down into elements by chemical processes.chemical processes.