User talk:Serebeth

Standard 1 atomic and molecular structure

1A elements are listed on the periodic table by their atomic number.

2A atomic number gibes the number of protons in the nucleus which is equal to the number of electrons in neutral atoms. So when elements are arranged by their atomic numbers families have same number valence electrons

3B electrons flow freely through metals so this question is really asking which one of these elements is a metal

4D metalloids or semimetals that straddle the zigzag line exhibit both properties of metals and non metals

5C the most active metal is F in the upper right hand corner and nonmetals

6A group 15 Ns family go from nonmetals to metalloids to metals Bi is a metal

7D metals are good conductors of heat and electricity malleable and ductile I is brittle not like a metal

8A metalloids straddle the zigzag line

9C elements in the same family or group have similar chem. properties due to similar electron configuration

10D group 14C family go from nonmetals to metalloids to metals Sn is a metal

11A group 15 N family go from nonmetals to metalloids to metals

12C arsenic As is a metalloid

13B elements in the same group or family have similar chem.. properties due to similar electron configurations

14C positive ions lose electrons and are smaller than their neutral atom. Down the patriotic table get bigger across get smaller

15D ionization energy and electro negativity to pull in an electron in a chemical increases across rows F to left of row

16A period 2 is going across the row from Li Be D trend is getting smaller across

17B metal make positive ions by losing electrons while nonmetals make negative ions by gaining

18B Fr is the most active metal in group 1 at the bottom

19C the electron sea model to explain metals ability to conduct heat and electricity has mobile electrons that can move from atom to atom.

20A larger atoms that have electrons that are further from the nucleus can lose the electrons easier. In group 1 atoms get bigger down the family so Cs has the greatest tendency to lose electrons.

21A 1= alkali metals 2= alkaline earth metals 17=halogens 18=noble gases group 1 and 2 are most similar with metals with + ions.

22B fluorine is the most active nonmetal

23C B is in group 13 with s 2 and p1 valence electrons number in front of is number of valence electrons.

24B iron is a transition metal and can have more than one charge roman numeral is the charge.

25C elements in the same family or group have similar chemical properties because similar valence electrons.

26A L makes K+1 ion by losing one electron.

27C noble gases are in group 18 noble gases with 8 valence electrons with similar chemical properties.

28C Sb5O-2 made to add up to zero to Sb2O-5

29D most of the atoms mass is located in the nucleus which is bery small and dense the nucleus has a positive charge negative electrons are far away from nucleus.

30A protons have +1 charge and mass of 1 amu.

31B neutrons have 0 charge and mass of 1 amu.

32B electrons have a charge of-1 and mass of 1/1836 amu electrons much less than protons.

33A electrons are negative and located far from the nucleus in orbitals.

Standard 2 chemical bonding

1A in covalent bond electrons are shared. They bond to themselves or close by one electronegative differs from 0-.2 it is a polar covalent bond.

2C electrons make the bonds with 2 electrons for a single bond 4 make double bond 6 a triple.

3B electrons given away or received then bond ionicly

4B electrons make bonds.

5B nonmetals bond to metals or if a nonmetal it has a weak bond.

6B metals lose electrons and make positive ions nonmetals gain electrons and make negative ions.

7B to make a covalent bond the elements must be close on the periodic table but 2 metals must be close to make a metallic bond.

8C they are asking which molecules could bond with H NH3+H=NH4

9A NaCl makes Na and Cl ions sugar does not.

10C to have a regular geometric pattern it must be a solid alternating Li and Cl would make one.

11B KCl makes K and Cl ions solid liquid and gas don’t have ions.

12C H2O in solid is ice which has regular geometric arrangement.

13D each dot in a lewis dot structure represents one electron Cl in group 17 has 7 valence electrons it fits the structure.

14D ionization energy increases across a row so elements in group 18 have highest ionization energy.

15D Aragon Ar is in group 18 so it fits Lewis dot structure.

Standard 3 conservation of matter

1C coefficients are the numbers in front to balance the equation like 6Al + 3O2=Al2O2

2B this is an oxidation reduction equation to balance charges aren’t balanced so add 4 on each side.

3A C3H8 +5O2 = 3 CO2 + 4 H2O coefficients in balance equation give ratios of moles and volume  of 5:3

4B coefficients ate the number put in to balance so it is balanced.

5D ratio can be found from the coefficients of the balance equation so it is 3:2

6A balanced equation is 3 CaSO4 + 2 AlCl3= Al2(SO4)3 + 3 CaCl2

7D balanced equation is H2 + Cl2= 2 HCl ratio is 1:2

8D Na in a Balanced equation means a mole of Na which has molar mass 23g.

9C Avogadro’s number 0.5 mole x (6 x 10 23) molecules/mole= 3 x 10 23 molecules

10C total atoms is 17 only 3 S atoms

11B Avogadro’s number

12A total atoms is 22 1 Ai 6C 9 H 6O

13B ratio of OH and HCl is 1:1 in the equation

14B one mole of O2 has a mass of 2 x 16 = 32 g /mole just as S has atomic mass of 32 g/mole

15B h2SO4 contains 2H atoms 1S atom and 4 O atoms total of 7 and is balanced.

16C NH4NO3 2 N atoms 4 H atoms 3 O atoms molar mass of 80g/mole 28g are N 35%

17C the empirical formula is the smallest whole number ratio of atoms in a molecule molar mass is multipliable of NO2 mass 92 is only possibility

18D Ca3(PO4)2 has 3Ca atoms 2P atoms 8 O atoms 310 g

19D standard molar volume is that 1 mole gas occupies 22.4 liters at STP 2g H2=1mole

20B balanced equation ratio is 1:1 Fe:Cu 1mole of Cu to make 1mole of Fe 21B balanced equation ratio of O2 and Al2O3 is 3:2 1 ½ moles of O2 to make 1 Al2O3

22D ratio in coefficients H to ammonia is 3:2 10 moles of H makes 6 2/3 moles ammonia

Standard 4 gasses and their properties

1B gasses have no volume no molecule interaction molecules move in straight line move faster at high temp.

2B Charles law V1/T1 = V2/T2 so V2 – V1x (283)/(273)

3D Boyles Law is pressure and volume are indirectly proportional P1Va = P2V2 so 1atm x 25ml/50ml = 0.5 atm

4A Boyles Law is pressure and volume indirectly proportional

5A Charles Law is Kelvin and volume are directly related

6B STP 0 C = 273 Kelvin 1atm = 760 torr = 14.7psi = 760 mm Hg = 101.325 kpa

7A 1atm = 760torr = then ½ atm = 360 torr at 0 C

8B temp is average kinetic energy of molecules C to Kelvin add 273 highest temp is 200 C of 473 Kelvin

Standard 5 acid bases and slats

1C NaOH + HCl = H2O + NaCl equal volumes neutralize to make water and salt (acid + Base)

2A H30 x OH = 10 -14 is Kw expression for water

3B H2SO4 +2 KOH = 2 H2O K2SO4 neutralize enough to make water

4C HNO3 + NaOH = H2O + NaNO3 ratio is 1:1

5B 2 NaOH + H2SO4 = Na2SO4 + 2H2O ratio is 2:1 twice as much NaOH to neutralize H2SO4

6C KOH + HCl = H2O + KCl ratio is 1:1

7D acid and base make water and a salt 8C CO3 -2 + H2O = HCO3 + OH H2O and OH conjugate acid base pair differ from H H2O OH

9D NH3 + H2O = = NH4 + OH H2O OH conjugate acid base pair differ H NH3 NH4

10D bigger Ka value stronger acid Ka = H3OxA/HA H3O + A make stronger acid

11A H2SO4 and HSO4 -4 conjugate acid base pair differ by H

12D lowest ph stronger acid HCl only acid

13A add acid ph decreases at 7 its neutral less than 7 is and acid greater than 7 is a base every number down is 10x more acidic

Standard 6 solutions

1A homogeneous mixture of solute dissolves in solvent looks clear heterogeneous mixture solid at bottom build in layers of liquid water is solvent things dissolve in it

2A gasses dissolve the most in cold solutions high pressure cold soda bubbles more than warm

3B CO2 = = CO2 pressure increases solubility CO2 increases

4B molar mass NaOH 40g/moles morality is mole over.5L is 2M

5B 2NaOH + H2SO4 = Na2SO4 + 2H2O ratio is 2:1

6B Morality moles/liters 10moles/5L = 2mole/L 2M

7C solution .6M and volume 20ml to 40ml concentration is ½ .3M

8A HNO3 + KOH = H2O + KNO3 ratio is 1:1

9C roadmap .5Lx 1mole/L x 128g/mole = 64g

10B volume x morality = moles .25L x amole/L = .25M

11D volume x morality 2L x 3M/L = 6M

Standard 7 chemical thermodynamics

1C temp is average kinetic energy of the molecules 5g at 400K is highest

2A temp goes down average kinetic energy goes down

3D products lower energy reaction exothermic releases energy

4D products higher energy reaction endothermic gained energy

5B Cl + Cl = Cl2 + energy bond form energy released exothermic

6C H2O + 68.3kcal = = Hs + ½ O2 reaction moves to left releases energy its exothermic

7D solution heats up dissolves salt gives off energy is exothermic

8A is energy is released reaction is exothermic would be negative

9C high temp molecules higher kinetic energy temp only increases with C

10C temp is same when melting or evaporation require energy so they are endothermic

11B liquid to solid + energy freeze is exothermic gas to liquid + energy condensation is exothermic

12B H20 = = H2O melt and freeze are at 0 C

13B solution heats dissolve salt give off energy exothermic

14A solid + energy = liquid melt is endothermic

15B liquid = solid + energy freeze is endothermic

16A liquid + energy = gas boil is endothermic

17D solid + energy = liquid melt is endothermic

18D 15g x 30cal/g = 450 cal

19B heat = mass x ^T 400 cal = 80g x 5 C original temp 10 C + 5 C = 15 C

20A heat = mass x heat fusion heat = 150g x 80 cal/g = 12000 cal = 12 kcal

Standards 11 nuclear processes

1B fusion is process where small nuclei bond hard to start they are both positive

2B positive protons in a nuclei repel positive protons in the other nuclei

3C regular chem. Reaction electrons move to make new bonds as it takes place atoms decay break apart and fuse

4A diagram shows 235U to 236U then breaks apart to 142Ba and 91Kr and 3 neutrons

5A fission heavy nuclei spits into lighter nuclei Parent to Daughter

6D fission reactors in power plants and bombs 235U fuels fission

7C diagram showed fission of 9 to 27 to 81 in a chain reaction

8B isotope atom top number is mass bottom is atomic number to balance both masses and atomic numbers must be the same

9A H 3 isotopes H1 H2 H3 all same number protons is coefficients

10D group 18 is noble gasses Rn atomic number is 84 mass of 222 no stable isotopes

11A group 16 oxygen family Po atomic number 84 mass 209 no stable isotopes

12A isotopes same element with different number of neutrons atomic number is different for all of them

13D 3 kinds of radiation alpha beta gamma alpha= 4,2He beta= o,-1e gamma= 0,0v

14B balance top and bottom numbers must add up 234,90Th = 234,91Pa + 0,1e

15A 9.4Be +4,2 He = 12,6C + 1,0n

16A 226,88Ra = 222,86Rn + 4.2He

17B As14C decays to 14N 6 C and 7 N protons increases

18D gamma is short wavelength high frequency so it most like high energy x-rays

Investigation section 1

1B large marks on ruler are centimeters smaller are millimeters wing length 2:1 cm and ends 3.5 cm so its 1.4 cm or 14 millimeters

2D brook trout represented by solid line

3A most accurate method is balance and repeat measurement 3 times without adjusting balance of uses

4B thermometer indicates current temp 37 C need increases by 6 C have temp desire 43 C

5A most people have heard that antibiotics become not effective if used too often because organism build resistance as new ones are made

6B although species A started high number of organisms its dying out while B started with less its living out on the grass

7A problem should say clear days not dear days algae grow to depth of 6 meters on clear days and 1 meter on cloudy days

8C graph rate on y-axis temp on x-axis enzyme works best at 40 C not above 58 C allows down at when cold but still active above 0 C

9A burning1 oz. proteins makes 147 cal fat makes 271 cal

10D the order of the scientific method is state problem formulate hypothesis perform experiment analyze data

11B new concept is hypothesis educated guess

12A experimental results to be considered valid must be reproducible

13B study behavior of any species must be natural environment with many of them

14A students wants to determine plants grow better in blue light or yellow study many types

15C new medicine tried control group usually a sugar pill people think they are getting better of worse sugar does not tell

16D experimental results to be considered valid must perform many times

17C solution turns from blue to yellow presence of acid must be indicator snail put in blue solution it turns yellow after 30 min so it must be producing an acid