Upcoming SlideShare
×

Final Review

• 398 views

More in: Education
• Comment goes here.
Are you sure you want to
Be the first to comment
Be the first to like this

Total Views
398
On Slideshare
0
From Embeds
0
Number of Embeds
0

Shares
4
0
Likes
0

No embeds

Report content

No notes for slide

Transcript

• 1. Significant Figures a.k.a.- sig figs
• 2. Significant Digits
• The certain digits and one estimated digit of each measurement are significant.
• Remember! Every time you make a measurement, you record all of the certain digits and one estimated digit.
200.5 4 g
• 3. Rules for Sig Figs
• Non zeros are always significant.
• Zeros between non zeros are significant.
• Zeros at the end of significant digits following a decimal point are significant.
• *They show precision in measurement.
• 4) Place keeper zeros are NOT significant.
• Zeros preceding significant digits.
• Zeros following significant digits without a decimal point.
• 4. Try These Examples
• 7.05940
• Final zero significant (follows decimal point)
• 6 significant digits
• 0.00135
• Leading zeros Not significant (place keepers)
• 3 significant digits
• 20,400
• Final zeros Not significant
• (place keepers – no decimal)
• 3 significant digits
• 5. Heat Calculations
• Heat (q)
• Energy transferred from an object at a higher temperature to an object at a lower temperature. (heat lost = -heat gained)
• q = mc  T
• q=mH fus
• q=mH vap
• 6. Heat Calculations
• A 10.0g sample of iron at 50.4 o C is cooled to 25.0 o C in 50.0g of water. Calculate the amount of heat lost by the iron.
• c iron= 0.449 J/g o C
• A 2.1g ice cube at –8.0 o C melts completely and warms to 12.5 o C. How much heat was required?
• H fus ice = 334 J/g
• c ice = 2.03 J/g o C
• c water = 4.18J/g o C
• 7.
• soluble – a substance that dissolves in a solvent
• insoluble – a substance that does not dissolve in a solvent
• solvation – the process of surrounding solute particles with solvent particles to form a solution
• 8. Solvation
• When a solid solute is placed in a solvent, the solvent particles completely surround the surface of the solid solute.
• If attractive forces between the solute particles and the solvent are greater than the attractive forces holding the the solute particles together, the solvent particles pull the solute particles apart and surround them.
• 9. + - - - NaCl Na = Cl = H 2 O H = O = + - + Process of Solvation - + + - + + + - - + + - + - - + - + - + - + - + + - + + - + + - + + - + +
• 10. Water- Universal Solvent
• Polar molecule
• Dipoles allow solvation of ions and polar molecules
• 11. Factors that Affect the Rate of Solvation
• Agitate the solution (stirring)
• increase the temperature of solvent
• increase the surface area of the solute
• 12. SOLUBILITY – refers to the maximum amount of solute that will dissolve in a given amount of solvent (at a specified temperature and pressure)
• saturated – a solution that contains the maximum amount of dissolved solute (for a given temp & pressure than a saturated solution)
• unsaturated – a solution that contains less dissolved solute (for a given temp & pressure than a saturated solution)
• 13. Units of Solubility
• g of solute
• 100 g water
• “ grams of solute per 100 grams of water ”
• 14.
• 15. Here are some for you to try.
• What mass of solute will dissolve in 100mL of water at the following temperatures. Also determine which of the three substances is most soluble in water at 15°C.
• KNO3at 70°C
• NaCl at 100°C
• NH4Cl at 90°C
• 16.
• supersaturated – a solution that contains more dissolved solute than a saturated solution at the same temperature
• - is above the solubility curve
solute will usually precipitate out of solution
• There are two main types of radioactivity: Natural and Induced
• Occurs in nature
• Usually large, unstable nuclei
• Occurs in three ways:
•  Particle (alpha particle)
•  Particle (beta particle)
•  Ray (gamma ray)
• 19. Alpha Decay
• A helium nucleus is released from the nucleus. ( )
• The mass decreases by 4
• The atomic number decreases by 2
• (Because the He nucleus has 2p + and 2n o )
• Alpha radiation can be stopped by a piece of paper. Cannot penetrate skin. Not dangerous.
• 20. Alpha Decay Example Notice that the uranium has changed into a new element, thorium.
• 21. Beta Decay
• An electron is released from the nucleus when a neutron becomes a proton.
• The mass is unaffected. (the mass of a neutron is roughly equal to the mass of a proton)
• The atomic number is increased by 1.
• Harder to stop and more dangerous.
• 22. Beta Decay Example Notice that carbon has changed into nitrogen.
• 23. Gamma Decay
• Pure energy is released from the nucleus.
• The mass and atomic number are unaffected.
• Stopped by lead. The most harmful to living tissue.
• 24. Gamma Decay Example No new element formed. Gamma radiation (energy) released.