Sig Figs and Matter/Energy Flashcards
What is the rule when multiplying and dividing two numbers in chemsitry?
You write your final answer in the least number of SF when x and dividing
PRACTICE:
1.271 x 1.6 = _______
1.271 has 4 SF, while 1.6 has 2 SF. Because we are multiplying, we write out final answer in the least number of SF based on the original values. 2 SF is the least number of SF, so the final answer will be written in 2SF
1.271 x 1.6 = 2.0336 = 2.0
T/F: This number has 4 sig figs - 1988
True
How many SF are in the number: 911?
3 SF
What is the rule when adding and subtracting numbers in chemistry?
The final answer is the least number of decimal places for + and -
Practice:
1.276 + 1.1001 = ______
1.276 has three deecimals places, while 1.1001 has 4 decimal places. The final answer is always written based on the least number of decimal places when + and -, so we must write out final answer with three decimal places.
1.276 + 1.1001 = 2.3761 = 2.376
Practice:
7.812 - 1.6 x 8.13 / 2.765
-2. OR -2
1 SF; for explanation look at notes
How many SF in: 540.
3SF
How many SF in: 540
2 SF
How many SF in: 18000 pens
5 SF
we count all the numbers if something designates a number
How many SF in: 2.9 x 10⁸
2 SF
dont count the 10⁸
What are the 2 big problems in the world currently?
- plastics
- chemicals in ozone layer
Define: Energy
ability to do work
What are the 4 types of energy. Know the definition of each
Thermal energy: is heat - will mainly focus on this in chem
Potential enerty: is stored energy
Kinetic energy: is E of motion
Radiant energy: is solar E from the sun
The energy given off is usually in the form of ________ energy
thermal (heat)
What are the 2 types of thermal (heat) energy in a chemical reaction?
Exothermic RXN
Endothermic RXN
What is the difference between an exothermic and endothermic RXN?
Types of Thermal (heat) Energy:
- Exothermic: (heat) E flows OUT the system
- Endothermic: (heat) E flow INTO the system
What ate the two units of heat energy? Which one is the SI unit for energy?
Untis of Heat Energy:
- Joule (J) - is the SI unit for heat E
- Calorie
Know how many Calories (C) are in a kcal that are in a calories (cal)
1C = 1kcal = 1000 calories
How many Joules (J) are in 1kJ?
1 kJ = 1000 J
How many Joules (J) are in 1 cal?
1 cal = 4.184 J
Convert 4.5 kJ to cal
Write the answer concerning the SF rules
= 1076 cal
= 1100 cal (2SF)
What is the difference between temperature and heat?
Temperature: a measure of how hot/cold a substance is COMPARED to another substance
Heat: is thermal energy that flows from a substance of a high temperature to low temperature
Heat moves from a substance of _____ temperature to _______ temperature
high
low
What is the formula for converting Celcius to Farenheight
F° = 1.8 (C°) + 32°
What is the formula for converting Farenheight to Celcius
C° = F° - 32 / 1.8
What is the formula for converting Celcius to Kelvin
K = C° + 273°
Practice: Liquid nitrogen is often used as a coolant for low-temperature experiment has boiling point of 77K. What is the temperature on the farenheight scale?
-321 F°
