Chapter 1 Chemical Foundations Flashcards
Scientific Method (definition)
The process that lies at the center of scientific inquiry.
Fundamental Concepts of Chemistry
- Matter is composed of various types of atoms.
2. One substance changes to another by reorganizing the way the atoms are attached to each other.
Scientific Method (steps)
- Make observations (collecting data)
- Making a prediction (formulating a hypothesis)
- Doing experiments to test the prediction (testing the hypothesis)
Measurement
A quantitative observation that involves both a number and a unit.
Hypothesis
A possible explanation for an observation.
Theory (Model)
A set of tested hypotheses that gives an overall explanation of some natural phenomenon.
Natural Law
Generally observed behavior formulated into a statement.
Law of Conservation of Mass
The observation that the total mass of materials is not affected by a chemical change. Mass is neither created nor destroyed.
SI System (International System)
An international agreement set up a system of units. It’s based on the metric system.
Mass
A measure of resistance of an object to change in it’s state of motion. It is measured by the force necessary to give a object a certain acceleration.
Weight
The force that gravity exerts on an object to measure it’s masses.
Certain Digits
Numbers that remain the same regardless of who makes the measurement.
Uncertain Digits
Number that must be estimated (varies). Report a measurement by recording all the certain digits plus the first uncertain digit.
Uncertainty
Any measurement involves estimates and cannot be exactly reproduced.
Significant Figures
Recording the certain digits and the estimated number. Uncertainty of the estimated number is assumed to be +-1.
Accuracy
The agreement of a particular value with the true value.
Precision
The degree of agreement among several measurements of the same quantity. It reflects the reproducibility of a given type of measurement.
Random Error (Indeterminate Error)
A measurement has an equal probability of being high or low. Occurs in stigma ting the value of the last digit.
Systematic Error (Determinate Error)
A measurement is either always high or always low.
Rules for Counting Significant Figures in Mathematical Operations
- Multiplication/Division- Sig Fig is the same number as the least precise measurement in the calculation.
- Addition/Subtraction- Same number of decimal places as the least specific measurement.
Unit Factor Method (Dimensional Analysis)
Unit conversions from English to metric systems.
Temperature
Tk(kelvin)=Tc(Celsius)+273.15
Tc=Tk-273.15
Tc=(Tf(Fahrenheit)-32F)(5C/9F)
Tf=Tc(9F/5C)+32F
Density
The mass of substance per unit volume of the substance.
D=Mass/Volume
Matter
Anything occupying space and having mass. Exists as a solid, liquid, or gas.
Mixture
Variable composition.
Homogeneous
Visibly indistinguishable parts; a solution.
Heterogeneous
Visibly distinguishable parts that can be separated.
Solution
A homogenous mixture.
Pure Substance
Constant composition, such as H2O.
Physical Changes
Boiling/freezing changes state (liquid/gas/solid)
Distillation
Separation of mixture components (volatility) through heat.
Filtration
Used with a solid/liquid mixture in a mesh filter.
Chromatography
A system employing a mobile and stationary phrase to separate mixtures.
Paper Chromatography
Strip of filter paper used for the stationary phrase with a drop of mixture that is dipped into a liquid.
Compound
Substance with constant composition that can be broken down into elements chemically.
Chemical Change
A given substance becomes a new substance with different properties/compositions.
Elements
Substances that cannot be decomposed into simpler substances.
