Chapter 2 Chemistry Review
What is the difference between accuracy and precision?
-Accuracy refers to the closeness of measurements to the correct or accepted value of the quantity measured. -Precision refers to the closeness of a set of measurements of the same quantity made in the same way.
What is the scientific method?
A logical approach to solving problems that lend themselves to investigation.
EQ: What are significant figures?
A measurement consisting of all the digits known with certainty plus one final digit, which is somewhat uncertain or estimated.
What is the difference between a Theory and a Law?
A theory is a broad generalization that explains a body of facts or phenomena. A law is a statement based on repeated experimental observations that describes some as
Review Notes: Chapter 2.3: Accuracy and Precision
Accuracy is how the close the measurement is to the true value while precision is how close several measurements are to the same number, whether it be correct or incorrect.
Define theory
An explanation for some phenomenon that is based on observation, experimentation, and reasoning.
Define hypothesis
An explanation that is based on prior scientific research or observations and that can be tested.
How do you calculate density?
Density is mass divided by volume.
Define system
Is a specific portion of matter in a given region of space that has been selected for study during an experiment or observation.
Define quantity
Is something that has magnitude, size, or amount. A quantity is not the same as a measurement.
EQ: Why is it important to measure with accuracy and precision AND use data to develop conclusions?
It is important to measure with accuracy and precision so that if an experiment was to be repeated the researcher will know if they did the experiment successfully or not based on the relation to the answer. Data is used to serve as evidence of the experiment's calculations, and as before, help the one experimenting understand how accurate their results are.
Define model
It is often an explanation of how phenomena occur and how data or events are related./ A pattern, plan, representation, or description designed to show the structure or workings of an object, system, or concept
What is KHDBDCM? OR What does the acronym King Henry Died By Drinking Chocolate Milk mean?
Kilometer, Hectometer, Dekameter, Base (grams, liters, meters), Decimeter, Centimeter, Millimeter
What is and how do you use Scientific Notation?
Numbers are written in the form M*10
What is the difference between Qualitative and Quantitative Observations?
Quantitative data is based off of numbers while qualitative data is based off of qualities such as taste, smell, touch, etc..
How do you round off significant figures?
SF are rounded off by this rule- if it is less than 5, drop everything thereafter; if it is greater than 5, round up by increasing the last digit by 1.
What are SI Units of Measurement?
The International system of units, which is the measurements system that is accepted worldwide.
What is the Metric Conversion Ladder?
The Metric Conversion Ladder is the ordered list of metric units from greatest to least with the standard units of measurements in the middle.
Review Notes: Chapter 2.3: Significant Figures
The easiest rule to use is the Atlantic/Pacific rule; first you must determine if the decimal is present or absent, which coincides with either Atlantic (Absent) or Pacific (Present). If the decimal is present, then you start on the left since the Pacific Ocean is on the left, and cross out all zeros until you reach a number 1-9, which is where you begin to count the significant figures. If the decimal is absent, you start on the right since the Atlantic is on the right and cross out all zeros until you reach a number 1-9, then you begin to count all numbers as significant figures.
What is the dimensional space method?
The method used when you have to convert a physical measurement from one dimensional unit to another; this is also known as the unit factor method or the factor-labeled method.
How do you add and subtract significant figures?
When adding and subtracting SF, round to the same number of decimal places as the measurement in the calculation (problem) with the least number of decimal places. (EX: 25.1 g + 2.03 g = 27.1)
How do you multiply and divide significant figures?
When multiplying and dividing SF, round to the number of sig figs in the least precise term used in the calculation. (EX: 25.20g x 25.003= 630.0)
How do you calculate significant figures?
You calculate significant figures with this rule- Calculated numbers cannot be more precise than the least precise measurement from which it was calculated. (However, from the rule Ms. Steven's taught us, you should use the same amount of significant figures as those used in the given value.)
EQ: How do you complete conversions using dimensional analysis?
You can derive conversion factors if you know the relationship between the unit you have and the unit you want. Such as the fact that 1 meter equals 10 decimeters. From the equality, you can write the conversion factors.
Define percentage error
a figure that is calculated by subtracting the accepted value from the experimented value, dividing the difference by the accepted value, and then multiplying by 100
Define derived unit
a unit of measure that is a combination of other measurements
What are Measurement Standards?
is an objects, system, or experiment that bears a defined relationship to a unit of measurement of a physical quantity. standards are a fundamental reference for a system of weight and measures, aganist which all other measureing device are compared.
Experimental Value
measured value determined experimentally in the lab
EQ: What are the stages of the scientific method?
observing and collecting data, formulating hypotheses, testing hypothesis, and formulating theories that are supported by data
Define density
the mass of an object in a given space; a physical property that varies with temperature
What is mass?
the quantity of matter an object contains
Define inversely proportional
the relationship between two variables whose product is constant
Define directly proportional
the relationship between two variables whose ratio is a constant value
Define volume
the space occupied by a sample of matter; changes with temperature
Accepted Value
true or correct value based on reliable references.