Chapter 1: Skills and Processes of Chemistry Flashcards
What is the modern process of scientific inquiry, based on observation, prediction and experimentation?
The Scientific Method.
What is a proposed explanation for an observation that generates testable predictions?
Hypothesis.
What is a statement of what will happen, assuming the hypothesis is correct?
Prediction
What is the difference between a hypothesis and a prediction?
A hypothesis is a proposed explanation, a prediction is a proposed outcome based on the hypothesis.
What is an experimental variable whose change is independent of the experiment?
Independent variable.
What is an experimental variable whose change depends on the experiment?
Dependent variable.
What is an independent variable you hold constant for the sake of the experiment?
Control variable.
What do you call information or properties that you can express numerically through measuring or counting?
Quantitative.
What are two things that quantitive data must possess?
- a number
- units
What do you call information or properties that you can only describe?
Qualitative
What is information that we collect from a primary source (our 5 senses, measuring equipment etc.)
Observation
What is information that we collect with the intention of representing graphically or visually?
Data
What is the act of drawing a conclusion based on evidence known or assumed to be true?
Inference.
What is the role of analysis in the scientific method?
Evaluating if the hypothesis was proven correct by the experiment, and the effect of sources of error.
What is an explanation of some aspect of the natural world, developed through the scientific method?
Scientific Theory.
What is a visual aide that represents or simulates something difficult or impossible to observe directly, based on current scientific theory?
Scientific model.
What is a summary of experimental evidence, stating that the outcome will always be the same under set conditions, with no explanation.
Scientific Law
What is a way of representing numbers in exponential form, for the sake of convenience?
Scientific notation?
What are the two components of a number written in scientific notation?
Decimal portion and exponential portion.
What does the exponent represent in scientific notation?
How many places and in which direction the decimal point needs to move to convert number back to standard notation,
The independent and dependent variables lie on which axes of a graph?
Independent: X axis.
Dependent: Y axis.
What is a single straight line that best fits the graphed data?
Best-fit line.
Which unit of measurement is considered the SI system (International System of Units)
The metric system
What system of measurements is composed of 7 units whose definitions evolve as technology improves?
The metric system.
What are the 7 base units of the metric system?
- Meter
- Kilogram
- Second
- Ampere
- Kelvin
- Candela
- Mole
What is the official SI unit for volume?
m3 (meters cubed)
What is the accepted base unit recognized for volume according to the SI system?
L (Litre)
Name two examples of SI accepted units that are not official “base units”
- Litre for volume (instead of m3)
- Minute for time (instead of seconds)
- Hour for time (instead of seconds)
What do you call an official SI unit whose definition is a manipulation of a base unit using either exponents or a combination of units?
A derived unit.
Units of a slope on a graph are categorized as what type of unit?
derived unit.
Which SI unit symbols are capitalized?
(L) Litre, any unit named after a person (Kelvin, Celsuis, Farenheit etc)
What measures the size of an object (hint: not “weight”)
Mass.
When it comes to recording SI units, do you use decimals or fractions?
Decimals (0.5 m/s not 1/2 m/s)
What is the word for how well a measurement agrees with that quantity’s true value.
Accuracy.
What is the word for how well numerous measurements agree with each other?
Precision.
What are the 2 definitions of precision?
1) How well numerous measurements agree with each other.
2) how certain a measurement is (0.300 is more precise/certain than 0.30)
What makes a group of measurements precise?
They are relatively equal to one another.
What makes a single measurement precise?
If it has low uncertainty.
What is an error that affects a group of results the same way?
Systematic error.
How does systematic error affect accuracy and precision?
Affects accuracy, not precision. (Measurements would be wrong, but all wrong in the same way).
What is an error that affects a group of results in an unpredictable and inconsistent way?
Affects precision, might affect accuracy. (only some of the measurements would be wrong, some could still be correct.)
What do you call an acceptable range of values within which we expect to find the true value of a measurement?
Range uncertainty.
How do you report range uncertainty?
Report the measurement, the unit, +/- the uncertainty, the unit again.
How do you find range uncertainty of a measurement?
Take the smallest division of the measuring device (ex. 1 mm) and multiply by 0.1 (10%)
What do you call an amount, with units, that refers to the difference between a measured value and an accepted value.
Absolute uncertainty (or Absolute error)
What do you call a ratio comparing a measurement’s uncertainty to the measurement, expressed as a percentage?
Relative uncertainty (or relative error).
Why would you need to know the relative uncertainty of a measurement?
To see how significant the error is. (1 mL error on a 5mL measurement is worse than 1 mL error on a 100 mL measurement).
What do you call the digits of a number that are meaningful, contributing to the number’s precision?
Significant Figures.
When using a measuring device, how many digits do you record?
All the digits you know for sure plus one estimated digit.
What is parallax error?
An illusion caused by observing the amount of water in a burette from above or below eye level.
Which digits are ALWAYS significant?
All digits that are NOT zero.
When is zero a significant figure?
- When it is between two sig figs (205)
- When it is a trailing zero AFTER a decimal point (25.0)
When is zero NOT a significant figure?
- When it is a leading zero. (0.04)
- When it is a trailing zero and there is NO decimal point. (1300)
When do you not use the sig fig rules on a number?
- When it is a defined number (24 hours in a day)
- Numbers obtained by counting (5 fingers on one hand)
When multiplying/dividing sig figs, the answer should have how many sig figs?
As many as the starting number with the FEWEST amount of sig figs in it.
At what point in a calculation do you round to correct sig figs?
Once, at the very end.
When adding/subtracting sig figs, where should the answer’s final digit be?
In the same column as the least precise final digit of the starting numbers).
How many inches in a foot?
12
What is the method of determining how to set up calculation by treating units as algebraic terms that cancel and compound like variables, allowing you to cancel unwanted units?
Dimensional analysis.
How do you start every dimensional analysis calculation?
With a statement of what you’re trying to find. (# of g=)
In dimensional analysis calculations, how do you represent a division statement?
As a fraction.
What is a fraction in which the numerator and denominator are equal, but expressed in different units.
Conversion factor.
T or f: conversion factors affect the number of sig figs in an answer.
False.
How do you convert a prefixed unit to another prefixed unit?
Convert to a base and then to the prefixed unit.
How do you convert a derived unit to another derived unit?
convert top unit and bottom unit one at a time, in any order.
What do you do when converting a measurement with an exponent?
Repeat the conversion factor the same amount of times as the exponent states.
What do you do when converting a measurement with an exponent to another measurement with an exponent?
Repeat conversion factor for both the starting exponent number and the final exponent number.
What is the average kinetic energy per particle in an object?
Temperature.
What is the freezing and boiling point of water? (Celsius)
O °C and 100 °C
What is the freezing an boiling point of water? (Fahrenheit)
32 °F and 212°F
What is absolute zero?
0 K, the coldest possible temperature, particles have no kinetic energy.
T or F, the ° symbol must always come before a temperature unit.
False, Kelvin has no ° before the K.
What is the freezing point and boiling point of water?
Kelvin
273.15 K and 373.15 K
