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I tried to take the cheap route to welding and got a $50 Gas(MAPP)/Oxygen welding/cutting torch from berzomatic. Man did I learn my lesson. Here's the summary of what happened, if you don't care just skip to the bottom.. The torch functions great and got me through a lot of cuts on my first project (using aluminum, another bad idea), but I realized that if I wanted to cut for more than 20 minutes or so at a time, without having to switch out the disposable oxygen tank with another one ($7 each!!), that I would need to get a much bigger, refillable tank. Another $75 bucks, but no big deal for a 'good investment'. So I did that and found out that the threads didn't fit right and that I needed an oxygen regulator (another $75..). Now I was happy that everything still functions well and my oxy supply is much better, but then I tried my first set of welds/brazes. The results were pretty horrific as you can imagine. The welds had absolutely no strength, no matter how much solder I used. Now I know that aluminum (especially in hollow tubes) is very difficult to weld with due to it's natural properties. So I've ended up spending just as much, if not more, than if I had just gotten a moderately cheap arc welder and have very little ability to actually weld/braze, just cut. _____________________________ What can I do to keep my current torch useful and at the same time enable me to make good strong welds? _____________________________ (I though about either using a different material like steel, or just getting an arc welder for welds and keeping my current one for cuts.)

Hummmm...Is there some reason why you are not using a wire feed MIG welder??? If you are welding aluminum you need to take a class on TIG welding and get the right equipment for it.

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In the industrial production of aluminum metal, while the aluminum oxide and electrolysis, aluminum is produced at one electrode and oxygen gas in other. For given quantity, the ratio of aluminum to the oxygen gas is (being given to reaction with coefficients not agreed upon): Al2O3 -> Al + 02 A) 2:3 B) 4:3 C) 3:2 D) 3:4 E) 2:2 Tank you. You would do the development?

It is always best to balance the equation to find out what is happening: 2Al2O3 ---> 4Al + 3O2 So the MOLAR ratio is 4:3; Answer B (and I assume this is the wanted answer) If you want the MASS ratio, you multiply these mols by the respective molar mass: Al... 4mols x 27g/mol = 108g O2...3mols x 32g/mol = 96g MASS ratio is 108 / 96 = 1.12 : 1 ...but this is not offered, so is NOT the answer wanted.

The following classifies the processes in the purification of water. State whether each is a physical or chemical change and why: 1) A coarse screen made of metal bars filters large particles and trash, such as bottles and cans. 2) Chlorine is added to kill bacteria and viruses. It also helps to remove dissolved hydrogen sulfide: H2S (aq) + 4 CL2 (aq) + 4 H2O(l)-------> 8 Cl- (aq) + SO2-4 (aq) + 10 H+ (aq) 3) A process called flocculation removes suspended particles, such as clay and micro-organisms. Lime, CAO, and aluminumn sulfate are added. They react together to form aluminum hydroxide. 4) The water is passed through a bed of graded gravel and sand in a filtering tank. 5) The water is often saturated with oxygen by spraying it into the air, which helps to remove volatile organic compounds. 6) The water receives a second treatment with chlorine to kill bacteria. Ammonia is added to make the chlorine last longer in the piping. Some cities add sodium fluoride.

1) physical, because nothing chemically is changing. The molecules are just being used to be a physical barrier. The metal still remains at the end. 2) chemical, because chlorine undergoes a redox reaction and becomes chloride (a totally different thing) 3) chemical, once again, keyword in this is "they REACT", something changes chemically, AlSO4 reacts to become AlOH3 4) physical, nothing changes, the water doesn't change, it is just filtered, a physical barrier, particles might be removed but it is still H2O 5) physical, nothing changes, water is still water, oxygen is still oxygen, it just becomes a mixture 6) once again, same as question 2, chlorine is undergoing a chemical change to react with something. It's this reaction that kills the bad stuff. A good rule of thumb, if it is not the same chemical formula at the end, it underwent a chemical change. If it is the same, H2O --> H2O, then it is not a chemical change.

A space shuttle has three main rocket engines and two solid-rocket boosters. At maximal power, each main engine burns 55 kg of liquid hydrogen and 440 kg of liguid oxygen every second; the exhaust H2O gas jets out at speed 4440 m/s. Each booster burns 5200 kg of solid fuel+oxydizer mix (mostly aluminum, polybutadiene polymer, and ammonium perchlorate) every second; the burn products jet out at speed 2630 m/s. (a) Find the thrust force of each rocket engine. (b) At liftoff, the shuttle assembly (the orbiter, the external fuel tank, and the two boosters) has mass 2.03·106 kg. If all the engines had their maximal thrust at liftoff, what would be the shuttle's acceleration? i have no idea how to do this...i calculated force for the individual gases for part a and got 244,200 kgm/s and 1,953,600 kgm/s ... is this right? and how do i do part B?

You've calculated the momentum of them (and add them together to get the dp for the main engine. You have to do the same to get the dp for the booster as well). But what you need is the force. Since that much mass is being accelerated every second, just divide by one second. F(me) = (55kg + 440kg) * 4440 m/s^2 F(me) = 2197800 N (Do the same for the boosters and then add to get total force) F(tot) = F(me) + F(boosters) With that, you'd have a rocket force. With gravity, you can calculate the gravitational force, and then subtract to get the net force. Finally, F=ma. F(tot) = F(thrust) + F(gravity) (Keep signs correct! Forces are in opposite directions!) a = F(tot)/m