Scientific Method
What is a hypothesis?
a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation
Is a zero before a decimal point significant? Example 0.45607
No, no zeros before the decimal are significant when it is solely a zero infront
What is the average of the following data set?
10, 12, 5, 3, 20
10
What is a compound?
a combination of two or more elements
What are the two types of properties?
Physical or Chemical
What is a theory?
A unifying principle that explains a body of facts
Is a zero after the decimal point significant? Example 45.0
Yes, zeros after a decimal point are significant
A student is testing the accuracy and precision of a scale by placing a 10g weight on the scale and recording the mass displayed on the scale screen. Are the following results accurate, precise, both, or neither?
Trial 1: 9.98g
Trial 2: 10.01
Trial 3: 9.99g
Both accurate and precise
What is a pure substance?
a compound made up of all the same element
What are the two types of changes that can occur?
Chemical or Physical
What is a law?
A concise verbal or mathematical statement of a relationship between phenomena that is always under the same conditions.
How many significant digits are in this number 4005.620
7
A student is testing the accuracy and precision of a scale by placing a 8g weight on the scale and recording the mass displayed on the scale screen. Are the following results accurate, precise, both, or neither?
Trial 1: 5.76g
Trial 2: 5.72g
Trial 3: 5.78g
Precise but not accurate
What is a Homogenous mixture?
a mixture with uniform composition throughout
A student has a white piece of paper and tears it into tiny pieces. What type of property or change is that?
physical change
What are the two types of observations and what do they mean?
qualitative- observable traits
quantitative- numerical
What is the rule with multiplication for how to determine the proper number of significant numbers to use? Solve 4.0(10.00) and report proper number of significant numbers
The answer will have the same number of significant figures as the number in the equation with the fewest number of significant figures.
Answer: 40.
What is systematic error?
when all of the results are inaccurate because of the scientist error or instrument error
What is a heterogenous mixture?
A mixture that is not uniform throughout
A student has a bottle of water and dumps a packet of liquid IV into it. What type of change or property is occuring?
Chemical change
A student says they have a theory as to why the library is five floors. Would a scientist use the word theory in the same way? Explain
No, a scientist would call this a hypothesis because it is not a unifying principle based on a body of facts
What is the rule for significant figures with addition and subtraction? Solve 15.1 + 2.45 and report proper number of significant figures.
The number of significant figures is reported to have the same number of decimal places as the number with the fewest number of decimal places.
Answer: 17.6
What is random error?
Only one or two of the data results are wrong out of a large collection of results that are accurate
Is lucky charms an example of a homogenous or heterogenous mixture?
Heterogeneous
The white piece of paper is used to take notes in class the paper is then dissolved in HCl. what is the physical change and property as well as the chemical change and property taking place?
Physical Change: The paper was a solid sheet of paper and then is dissolved by the HCl into a liquid
Physical Property: Initially it is white then it is a liquid
Chemical change: The paper is dissolved in the HCl so the elements in the paper and the HCl react with one another to change the chemical composition
Chemical property: the formula for paper pre and post HCl