Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
PhD chemist here. I'm assuming you're talking about the theoretical mass of O2
Here are the three molar masses:
KClO3:122.55 g/mol
KCl:74.55 g/mol
O2: 32 g/mol
This is your reaction and you know that you have 1.212 g of KClO3.
2 KClO3 -> 2 KCl + 3 O2
First up calculate the moles of KClO3
n = 1.212 g/122.55 g/mol = 9.890*10-3 mol
You know that for every 2 moles of KClO3 that decomposes you produce 3 moles of O2
n O2 = (3 moles O2/2moles of KClO3)*(9.890*10-3 mol KClO3) = 1.484*10-2 mole O2
m O2 = (1.484*10-2 mole)*(32 g/mol) = 0.475 g
THis mass is the expected value meaning that if you were to go perform this experiment in a lab you would expect to produce this much gas. The actual value (or experimental value as it is sometimes called) is the amount of gas that you produced and measured experimentally. You do not use the molar mass in this equation.
I have a couple of questions if you don't mind. They're not problem-solving questions, they're descriptive.
What's a chemical I can use to remove the oil off of keyboards? I tried isopropanol, hexane, and monitor wipes. (They don't make keyboard wipes.).
What do you think is the most dangerous endothermic reaction?
Strongest known metal bond? (We all know the strongest known covalent bond is C=O, but I couldn't find bond strengths in metals.
Thanks.
I'm a physical chemist by training. Now to answer your other questions:
Out of all of those you mention isopropanol is probably the best one. Hexanes risk damaging the plastic and it isn't a good idea for you to be exposed to them.
I'm not sure how you quantify danger in this case? In terms of toxicity of of the products or in terms of amount of heat released? If it's the latter then you need to consider exothermic reactions. Endothermic reactions absorb heat from their surroundings to make the reaction go forward while exothermic ones release heat upon reaction and therefore are more dangerous. The combustion of explosives is exothermic. The oxidation of thermite is probably the most exothermic reaction known.
I believe tungsten-tungsten is the strongest metal bond.
I'm a physical chemist by training. Now to answer your other questions:
Out of all of those you mention isopropanol is probably the best one. Hexanes risk damaging the plastic and it isn't a good idea for you to be exposed to them.
Well I guess you're not an organic chemist, but I dunno if anyone can argue isopropanol is better than ethyl alcohol?
So this question was for oils in general, then I asked, what is the oil off of human fingertips? According to 1 biochemistry professor, omegas. I guess he meant omega fatty-acids. So I asked an organic professor about removing omega fatty-acids from keyboards, and my recommendation was dichloromethane. Which I haven't tested.
Quote:
Originally Posted by 514gal
I'm not sure how you quantify danger in this case?
In terms of PVnRT.
In terms of toxicity, well 1 professor suggested the production of cyanide gas is the most dangerous.
1 physical chemistry professor thinks implosions are potentially dangerous - where you get "sucked in." But inorganic professors will dispute that, citing endothermic reactions don't always go to completion.
Quote:
Originally Posted by 514gal
I believe tungsten-tungsten is the strongest metal bond.
Yea I heard this 1 too.
But when looking at some of the tallest buildings like the Sears Tower, they're most likely built off hcp-iron, or whatever you call, iron surrounded by 12 iron atoms rather than 8. I'm guessing that's the most standard for strongest.
Well I guess you're not an organic chemist, but I dunno if anyone can argue isopropanol is better than ethyl alcohol?
So this question was for oils in general, then I asked, what is the oil off of human fingertips? According to 1 biochemistry professor, omegas. I guess he meant omega fatty-acids. So I asked an organic professor about removing omega fatty-acids from keyboards, and my recommendation was dichloromethane. Which I haven't tested.
In terms of PVnRT.
In terms of toxicity, well 1 professor suggested the production of cyanide gas is the most dangerous.
1 physical chemistry professor thinks implosions are potentially dangerous - where you get "sucked in." But inorganic professors will dispute that, citing endothermic reactions don't always go to completion.
Yea I heard this 1 too.
But when looking at some of the tallest buildings like the Sears Tower, they're most likely built off hcp-iron, or whatever you call, iron surrounded by 12 iron atoms rather than 8. I'm guessing that's the most standard for strongest.
I don't think you are understanding the answers your professors are telling you. "Omega" fatty acids aren't any different than "Alpha" fatty acids: the omega naming convention just counts from the tail end rather than the polar carboxylic acid functional group. The key to cleaning "oils" off of plastic is much more about shearing force than solubility.
PV=nRT is just an algebraic expression of the ideal gas law. I cannot see how this relates to dangerous endothermic reactions. I don't think there is any endothermic reaction that is dangerous because of its endothermicity, but there are plenty of very toxic substances with endothermic synthesis steps (such as nerve gas, alkylmercury compounds, and certain toxins.
In the scheme of things, implosions are not all that dangerous. The most powerful vacuum ever created on earth only has a roughly 1 atm pressure difference from the ambient air. I have collapsed bell jars when doing vacuum processes and it is a bit underwhelming.
Material properties are more complex than just "strength". When evaluating materials, their response to different types of forces such as shear, compression, tensile, etc. are more important than the directional atom-level interactions. The previous poster's observation than tungsten has the "strongest" bonds is correct in that tungsten has the highest melting point of all metals. The structural building properties of metals are based on other characteristics.
I don't think you are understanding the answers your professors are telling you. "Omega" fatty acids aren't any different than "Alpha" fatty acids: the omega naming convention just counts from the tail end rather than the polar carboxylic acid functional group.
Huh.
Does this have something to do with dichloromethane?
Quote:
Originally Posted by Chemistry_Guy
PV=nRT is just an algebraic expression of the ideal gas law. I cannot see how this relates to dangerous endothermic reactions. I don't think there is any endothermic reaction that is dangerous because of its endothermicity, but there are plenty of very toxic substances with endothermic synthesis steps (such as nerve gas, alkylmercury compounds, and certain toxins.
In the scheme of things, implosions are not all that dangerous. The most powerful vacuum ever created on earth only has a roughly 1 atm pressure difference from the ambient air. I have collapsed bell jars when doing vacuum processes and it is a bit underwhelming.
What about... endothermic chain reactions?
Quote:
Originally Posted by Chemistry_Guy
Material properties are more complex than just "strength". When evaluating materials, their response to different types of forces such as shear, compression, tensile, etc. are more important than the directional atom-level interactions. The previous poster's observation than tungsten has the "strongest" bonds is correct in that tungsten has the highest melting point of all metals. The structural building properties of metals are based on other characteristics.
So, can you list any examples of some characteristics where steel is stronger than tungsten, and vice versa?
I've heard even concrete has some characteristics stronger than steel (aside from fire) but steel is much cheaper and therefore more widely used.
Also, don't forget heat of evaporization and enthalphy of evaporation. (The heat of vaporization is proportional to bond strength.). The enthalpy of vaporization is the heat of vaporization at constant pressure.
Does this have something to do with dichloromethane?
What about... endothermic chain reactions?
So, can you list any examples of some characteristics where steel is stronger than tungsten, and vice versa?
I've heard even concrete has some characteristics stronger than steel (aside from fire) but steel is much cheaper and therefore more widely used.
Also, don't forget heat of evaporization and enthalphy of evaporation. (The heat of vaporization is proportional to bond strength.). The enthalpy of vaporization is the heat of vaporization at constant pressure.
Thanks.
Science questions can be confusing for a non-scientist because a lot of the scientific vocabulary words, which mean something very specific in a scientific context, are used in everyday speech to mean a lot of different things. For example, in chemistry the term "reaction" means specifically the path from reactants to products. If you start with A and end up with B, A --> B is the reaction. While this definition gets stretched to mean different things (such as ions crossing a membrane, inside --> outside) it does not take into account the possible locations where the reaction is happening. That is why "dangerous" is not really a term that a chemist would use to describe a reaction, as it applies to the situation where the reaction is happening more than the reaction itself.
We also try to avoid using terms like "better" to describe very general characteristics such as material properties. When something is clearly defined, such as nucleophilicity, we might say that X is a better nucleophile than Y. However, something as complex as material properties have too many nuances for one substance to have "better" characteristics. For example, what is the "best" flexibility for a structural material? You can't answer that without specifically describing the application.
I suggest you read a material science textbook or wiki article and familiarize yourself with terms such as young's modulus, hardness, tensile strength, toughness, poisson's ratio, and hysteresis. You will see that many different materials are well suited for different construction types, and that "best" isn't very useful as a descriptor.
Does this have something to do with dichloromethane?
What does alpha fatty acids, and omega fatty acids, have to do with dichloromethane - was dichloromethane meant for 1 type of fatty acid and not the other?
Quote:
Originally Posted by NealIRC
What about... endothermic chain reactions?
Can endothermic chain reactions be as dangrous as exothermic chain reactions?
Quote:
Originally Posted by NealIRC
So, can you list any examples of some characteristics where steel is stronger than tungsten, and vice versa?
So, can you list any examples of some characteristics where steel is stronger than tungsten, and vice versa, in terms of Young's modulus, hardness, tensile strength, toughness, Poisson's ratio, and hysteresis?
Quote:
Originally Posted by NealIRC
I've heard even concrete has some characteristics stronger than steel (aside from fire) but steel is much cheaper and therefore more widely used.
Also, don't forget heat of evaporization and enthalphy of evaporation. (The heat of vaporization is proportional to bond strength.). The enthalpy of vaporization is the heat of vaporization at constant pressure.
Thanks.
So which material substance has the strongest heat of vaporization.
-
Thanks.
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
