Catalyst – March 3(6), Describe the difference between single- replacement and double-replacement reactions. 2. Write general equations for S-R and D-R reactions. HOMEWORK OUT PLEASE

Today’s Agenda  Catalyst  Chemistry Prom 2010 Day 3!  Practice and Work Time  GEE PREP!  Exit Question

Today’s Objectives  SWBAT predict the products of combustion reactions.

Combustion Reactions

It’s getting hot in here… Key Point #1: A COMBUSTION REACTION is one in which a hydrocarbon burns in the presence of oxygen gas, releasing heat and light A hydrocarbon is any compound made of only hydrogen and carbon Ex: CH 4, C 2 H 4

We be burning… Is C 50 H 102 a hydrocarbon? Will it react with O 2 ? Will it form CO 2 and H 2 O?

Combustion Examples Predict products of the reactions! 1. CH 4 (g) + O 2 (g)  2. C 2 H 2 (g) + O 2 (g)  CO 2 (g) + H 2 O(g)

Practice  Write the chemical equation for ethane gas (C 2 H 6 ) burning in air. Then, answer the questions below: 1. If you see the word “BURNING” in a word equation, that means it is a ______________ reaction. 2. What are the reactants? 3. What are the products? C 2 H 6 + O 2  CO 2 + H 2 O

Your Turn!  Write chemical equations for the following reactions: 1. Methane gas (CH 4 ) combusts. 2. Butene gas (C 4 H 4 ) burns in the air. 3. Ethyne gas (C 2 H 2 ) goes through a combustion reaction.

All 5 Chemical Reactions  There are 5 types of chemical hook- ups (reactions) at the prom this year. 1. Synthesis 2. Decomposition 3. Single Replacement 4. Double-Replacement 5. Combustion

Let’s come together A SYNTHESIS REACTION is one in which two or more substances combine to form one new substance.  A + B  AB  Two substances are at the Chemistry Prom, dancing alone…they decide to hook up…

I don’t think this is working out… A DECOMPOSITION REACTION is one in which one substance breaks down into multiple substances, usually with the help of some kind of heat or energy  AB  A + B  A couple at the Chemistry Prom decides to break up

Drama on the Dance Flo!  A SINGLE-REPLACEMENT REACTION is one in which a single element replaces a similar element in a compound  A + BX  AX + B  A couple is dancing, and someone else cuts in

Swing Fever! A DOUBLE-REPLACEMENT REACTION is one in which ions switch places. You must KRISS-KROSS to write ALL formulas!  AX + BY  AY + BX  Two couples are dancing and decide to switch partners!

It’s getting hot in here… Key Point #1: A COMBUSTION REACTION is one in which a hydrocarbon burns in the presence of oxygen gas, releasing heat and light A hydrocarbon is any compound made of only hydrogen and carbon Ex: CH 4, C 2 H 4

Work Time  Please complete worksheet!  Any Chemistry Prom King or Queen nominations?  King Nominees:  Nathan  Granville  Stephon  J’Don  Carlton Queen Nominees: Jandolyn Ida Breonne M. Breionna Chyna Gina

GEE Prep Science Task: Pile Driver

 #1 Scoring notes:  Possible variables to hold constant:  the mass of the weight (or the weight)  the starter holes drilled in the wood blocks (same depth or size)  the kind of nail (size, composition, mass, etc.)  the kind of wood block (size, composition, etc.)

 #2 Scoring notes:  Part A: Accept from 4.5 cm to 5.0 cm as reasonable.  OR…  The nail will be driven into the wood a distance that is about double that when it was dropped from 20 cm.  Part B: Data for trials 4 and 6 show that when the distance the weight falls doubles, the distance the nail is pushed into the wood also doubles. Trial 2 shows that when a 2-kg mass falls 20 cm, the nail is pushed into the wood 2.4 cm. Therefore, when the same 2-kg mass falls 40 cm, the nail should be pushed into the wood 4.8 cm (=2.4 cm × 2).  Note: Advanced students may recognize that trials 4 through 6 indicate the variables are directly proportional and explain their prediction based on a direct proportion.

 #3 Scoring notes:  Sample answers:  Pile drivers are much larger than the model.  Pile drivers use much heavier weights than the model.  Pile drivers get their energy from burning gasoline in a motor, not from humans lifting the weights.  Piles are driven into soil, not wood.  Piles are not made of the same material as nails.  Piles don’t always have points on the ends as the nails did.

 #4 Scoring notes:  Sample answers:  gravitational potential energy (or “energy of position”) when the weight is raised above tabletop  kinetic energy (or “energy of motion”) when the weight is in the process of falling  kinetic energy when the weight is in the process of being lifted  kinetic energy of nail as it moves farther into the wood after being struck  sound energy generated by the collision between the weight and the nail heat energy as a result of friction between nail and wood or string and pulley  chemical energy in the food the students ate that gave them energy to do the investigation  mechanical energy as a result of the moving parts of the pile driver

GEE Prep More Questions

Biology  Question: Suppose a change occurs in one of the molecules making up the DNA in the nucleus of a cell.  A. Explain why this change could affect a protein that is made in the cytoplasm.  B. Explain one role RNA plays in making the protein.

 Part A: DNA contains the code for making the protein (or for sequencing the amino acids). If the DNA changes, the new coding could be for a different protein (or sequence of amino acids).  Part B: Possible answers for part B include:  Through, RNA, the DNA code leaves the nucleus and guides the construction of the protein in the ribosomes in cytoplasm. OR  RNA is used to pick up amino acids and bring them to where the protein is being made (that is, the ribosome). OR  RNA makes sure the building blocks of proteins (that is, amino acids) are put in the correct order in the protein.

Food Chain  Use the food chain below to answer the question.  This food chain shows the direction energy flows from a producer to a third-level consumer. In terms of energy, explain why there would be many more mice than hawks in an environment involving this food chain.

 2 points:  Because of energy loss in transfer, it takes a lot of energy (food, individual prey) to go from one level in the food chain to the next. Higher trophic levels have less energy available than lower levels do. About 90 percent of the energy is lost during the transfer from one level to the next. Only about 10 percent of the energy available is transferred from one level to the next.  1 point:  Response simply states that it takes many mice to feed a snake through its lifetime and many snakes to feed a single hawk at the top of the chain.  Note: The 1-point response will most likely fail to provide an explanation in terms of energy.

Earth Science  Question: Natural processes and changes on Earth can take place in a short period of time or can take millions of years.  A. Describe an example of a process or change that takes place in a short period of time.  B. Describe an example of a process or change that takes millions of years.

 Short-period processes or changes:  earthquakes  volcanic eruptions  flash floods  tornadoes  hurricanes  landslides  avalanches Long-period processes or changes: changes in the oxygen content of the atmosphere plate tectonics (uplifting and weathering of mountains) formation of coal deposits formation of sedimentary rock Either short- or long-period processes or changes (depends on description) delta formation coastal erosion river changes course (meandering rivers)

Exit Question 1. What is a hydrocarbon? 2. What other substance must be present in order for a combustion reaction to take place? 3. What are the products of combustion reaction?