Conceptual Chemistry

Transcription

1 Conceptual Chemistry

2 1. Use examples to explain the various branches of science. 2. Distinguish between qualitative and quantitative observations. 3. List the SI units of measurement and common prefixes. 4. Convert units using dimensional analysis. 5. Diagram and explain the various components of experimental design. 6. Calculate the density of an object from experimental data.

3 Uses for Science: i. Analytical ii. Classification iii. Invention iv. Scientific Method

4 Laboratory analysis Finding what something is made of Example: forensics 1. Quantitative numerical amounts measured 1.9 cm, 2.00 g, 55.3 o C 2. Qualitative measured with senses short, heavy, hot

5 Common language Example: Biology domain, kingdom, phylum, class, order, family, genus, species Humans: domain: Eukaryota kingdom: Animilia phylum: Chordata class: Mammalia order: Primates family: Hominidae genus: Homo species: sapiens

6 Creating or producing by exercise of the imagination No rules Example: mobius strips

7 Method of research in which a problem is identified, relevant data are gathered, a hypothesis is formulated from these data, and the hypothesis is empirically tested Used to prove something Strict rules

8 Branches of Science 1. Biological 2. Physical 3. Earth

9 The study of living things (bio = life) Video Example 1 Video Example 2

10 The study of Non living materials and or energy Video Example 1 Video Example 2

11 The study of Non living earth features Video Example 1 Video Example 2

12 Link 1 Link 2

13 Used for formal research Observation/Stating a Question or Problem Gathering Information Forming a Hypothesis Experimental Design Recording and Analyzing data State a Conclusion Repeat

14 Varies depending on the project. Looking to prove or disprove a point.

15 Research what is already known. Use and keep track of credible sources.

16 If then because

17 Change only 1 variable. Controls: (Normal unchanged) Experimental Group:(Changed) Independent Variable: I change the I ndependent variable Dependent Variable: Outcome you hope depends on your change

18 Data Tables Graphs Calculations

19 Based on experimental results Use gathered information to back up question or problem

20 Multiple trials lead to more reliable results.

21 Draw a picture of the control group and experimental group. Label each group. Try to describe the dependent and independent variable. Control Experimental

22 Metric Ruler Metric Ruler

23 Graduated d Cylinder lid

24 Graduated Cylinder Graduated Cylinder

25 Measurement using the metric system. Basic Units Also called Standard dinternational or S.I. Units

26 Quantity Units Symbo Example Length meters l m average human ~ 1.6 m Mass kilograms kg 1 penny ~ 1 g Volume Liters L 2 L bottle Density mass/volume g/ml or g/cm 3 density of water ~ 1 g/ml Temperatur kelvin K room temperature = 293 K e Time seconds s 1 min =60 sec Pressure Pascals Pa 101,000 Pa = sea level

27 Basic Unit is kelvin. It is found by o C+ 273 = kelvin

28 Remember: o C+ 273 = kelvin 0 o C is actually 273 Kelvin. Still lots of energy. o 0 o C = 273 K 100 o C is equal to 373 K o 100 o C = 373 K 273 o C is equal to 0 K o 273 o C = 0K o This is called absolute zero. Everything stops.

29 1. Antarctica can get as cold as 100 o C. How many K is this? 2. If global lwarming continues, Earth could earn an average temperature of 313 K. How many o Cwould this be?

30 Prefix Symbo Meaning Multiplied size Example tera l T trillion 1,000,000,000,000 terabytes giga G billion 1,000,000,000 gigabytes mega M million 1,000,000 mega million kilo k thousand 1, kilometer race = 7.2 mi centi c hundredth 1/100 finger nail milli m thousandth 1/1,000 thickness of penny micro µ millionth 1/1,000,000 human cells Nano n billionth 1/1,000,000,000 DNA

31 Density the ratio of the mass of an object to its volume Density = mass / volume The density of substances changes with temperature.

32 Show with pictures, label all values, and show math 1) Measure dimensions of Block (cm) 2) Measure mass of Block (g) 3) Calculate l Density of Block

33 Show with pictures, label all values, and show math 1) Mass of empty Graduated dcylinder 2) Measure 50 ml of Water in Cylinder 3) Mass of water and Cylinder together 4) Calculate Mass of Water 5) Calculate l Density of Water

34 Show with pictures, label all values, and show math 1) Measure mass of object 2) Use partially full G. Cylinder record volume 3) Place object in G. Cylinder record new volume 4) Calculate l Volume of object 5) Calculate Density of object

35 f What is the density of an object with a mass of 4.00 g and a volume of 4.00 ml?

36 Density is the ratio of the mass of an object to its volume Water density = 1.0 g/ml Cork density is less than 1.0 g/ml The formula for density is D= mass / volume

37 If you have two objects of the same size, and object A is more dense than object B, which one will have more mass?

38 Dice

39 Wax

40 Corn Syrup

41 You must always SHOW WORK when converting units. This will pay huge dividends for your entire science future.

42 Any number can be written over one. It will not change the value. o 7/1 = 7 Any number divided by itself equals one. o 7/7 = 1 If you multiply by one, it will stay the same. Any amount divided by the exact same amount equals one.

43 1. Write down the given number, with units. 2. Choose a conversion factor that will get you away from what you re GIVEN, and get you to what you WANT. Remember, the TOP and BOTTOM of the fraction must be an EQUAL amount, so it really only equals ONE. 3. Place your conversion factor next to the given number so that it is MULTIPLIED using A FRACTION. Make sure what you WANT is on top, and what your getting rid of is on BOTTOM. 4. If multiple changes are needed, just multiply by multiple li l conversion factors. 5. Cross of units that appear on TOP and BOTTOM. The only unit left should be the one you WANT. 6. In your calculator, l multiply l all TOP numbers, divide id by any BOTTOM numbers.

44 One step problem: Convert 3 weeks to days. Convert 62 inches to centimeters (1 inch = 2.54 cm) l kl l Convert 75 miles to kilometers (0.62 miles = 1 km)

45 Two step problem: Convert 3 weeks to hours. Four step problem: Convert 3 weeks to seconds.

46 1. How many fingers would be on 12 hands? 2. How many centimeters would be in 200 meters? 3. How many kilometers is 2,043 meters?