Chemical Equation
Explain what a chemical formula is.
It combines symbols of different elements to represent molecules
N₂ + H₂ → NH₃ Balance this equation
N₂ + 3H₂ → 2NH₃
What does synthetic mean?
Synthetic is a chemical or resource made by humans.
Shelled animals in the ocean can have their shells dissolved by carbonic acid when the ocean becomes acidic. Over time, how might carbonic acid in the oceans affect a food web that contains these animals?
When they can't build their shells, they are easier prey. Eventually they may go extinct and there will not be enough food for the predators to eat and the food web collapses.
Which two properties of an egg change when it is cooked and are those chemical or physical changes?
What does a subscript tell you next to an element?
How many atoms of that element there are.
N₂ + 3H₂ → 2NH₃ How many hydrogen atoms are on the products side of the equation?
6
What is a natural resource. Give an example.
A natural resource is anything naturally occurring in the environment that humans use. Ex.cotton
What is the difference between the structures of monomers and polymers?
A polymer is a long chain and monomers are single units.
What does a change in properties indicate?
That a chemical change has occured?
What does a coefficient tell you that is in front of a molecule in a chemical equation?
How many of that molecule you have.
N₂ + 3H₂ → 2NH₃ - If I change the 2 in front of the NH and remove the subscript 3 after the H would that be the same molecule? Why or why not? Explain.
No, 2NH₃ means that I have 2 molecules of NH₃, but if I write it as 6NH then that would mean I have 6 molecules of NH and NH is not the same molecule as NH₃
What is a polymer?
Long chains of molecules that are made up of repeating monomers.
A website publishes an article arguing that synthetic materials do not benefit society because they are created in a lab. Does the evidence support the conclusion? Do you think the website is a reliable source? Explain.
It isn't reliable. The evidence does not support the conclusion. You have to acknowledge that synthetic products have benefited many people, even if the products also carry risks.
A student uses flour, sugar, eggs, and butter to bake a cake. What type of chemical reaction is this? Explain
Endothermic reaction - it is taking in the heat.
When balancing an equation what numbers do you change to balance it?
The coefficients.
Is mass conserved in an open system?
Yes, it just seems it is not because it escapes into the air
Why do chemists synthesize polymers in a lab?
Sometimes they are not commonly found in nature or better suited for particular functions. Polymers are both strong and flexible.
What are the benefits and drawbacks for producing synthetic foods. Give two benefits and one drawback.
benefits: make foods safer to consume, makes food last longer, cheaper
drawbacks: could be health risks.
Exothermic reaction - it is giving off heat.
In a chemical equation what does the arrow point to?
The product.
Explain why we balance equations.
To show that they law of conservation of mass does prove true. That mass cannot be created or destroyed only transferred.
Give a benefit and a drawback of using synthetic materials such as plastic bags?
benefit: flexibility/hold things
drawbacks: harmful to environment/allergic reactions
During a chemical reaction, if not all the reactants react, is the mass of the reaction before and after the same given that nothing is added or taken away from the reaction system? why or why not?
Yes, because the same number of atoms is still there.
What is the only way to be certain that a chemical reaction has occurred?
The only proof is that one or more new substances have been produced.