- A spontaneous reaction is a reaction that continues by itself once it begins.
- The two questions that must be addressed to determine whether a spontaneous reaction can occur are, if the change gives off heat energy or if the change results in the particles becoming more disorderly.
- if the bond is being broken and requires energy input it is endothermic but if the bond is being formed it requires the release of energy, making this exothermic.
- The energy comes from the bonds keeping the atoms together.
- Powdered iron, magnesium and salt water were used to increase the reaction time in a MRE heater.
- A Catalyst speeds up chemical reactions by providing a lower-energy alternative pathway for the reaction to take place.
- The diagram with the catalyst starts at a much higher energy and the slope gradually becomes negative at the end from losing energy
In this chem talk we talked about Enthalpy. There were two main reactions, Exothermic and Endothermic. Questions that are freequantly asked dealing with these reactions would have to be, “Will it conitinue” and “How fast will it occur”. A chemist can know if these reacitons are spontaneous by testing them. The word Spontaneous is defined by a change, once begun, that continues without an input of energy. How spontaneous something is, relies on the factors and whether it is favorable or not. Kinetics which is a theory, can be used to study the reaction rates and how they can be affected by variables such as concentration, partial size, and temperature. This chem talked introduced many different topics so i am interested to see how they all coexist and are related to labs we do in the classroom.
- NaCl conducts electricity because when the crystal is dissolved in water the sodium ions and chloride ions separate from the crystal. They can move around in water. Molecular compounds do not break up into ions when they dissolve. They can not move around in water and can not conduct electricity, which is why C12H22O11 cannot.
- An electrolyte is a substance that dissolves in water to make solutions that conduct electricity and non-electrolytes are molecules that do not form ions in a solution.
- The Zinc electrons come from the zinc metal and then travels through the wire. Reduction takes place when the electrons reach the copper and the copper ultimately takes them.
- The anode of a battery is when oxidation takes place and the electrons are released into the circuit. The anode is negative when giving away, in this case, electrons. It is where the electrons are released.
- The cathode of the battery is where reduction takes place and the electrons are received. The cathode is positive when receiving. It is where the electrons are received.
In this chem talk we first talked about electrolytes, which are substances that dissolve in water to make solutions that conduct electricity. I learned that for a solution to be able to conduct electricity, there are two conditions. Charged particles must be present and the charged particles must be able to move around. The compounds are made up of a positively charged metal ion and negatively charged metal ion to balance the charge. Molecules that do not form ions in solution are non-electrolytes. I also learned that battery is composed of two half cells. The half cell where oxidation takes place is called the anode. The other half-cell where reduction takes place is called the cathode. The term half cell is because on cannot exist without the other. This kind of makes me think of twins. Wherever one is the other is right by their side. When reading this chem talk I thought I was missing something. I did not understand where the activity series came into play in this section. Soon enough I realized that the activity series has to do with which way the electricity would run in a battery. Whichever element is first and more reactive will react spontaneously. Also the farther apart two metals are from each other within the activity series the more powerful the metal/other metal ion reaction will be.
I learned in this chem talk that much of chemistry grew out of the field of alchemy. The goal of an alchemist was to create gold out of other metals. Alchemist discovered that some metals react more easily with most metal ion solutions than other metals do. This had to do with the origin of the activity series. I also learned about a special class of reactions called redox and oxidation which is giving up electrons. Reductions is receiving electrons, which is why and oxidation equation turned backward represents a reduction. Because they are both opposites. I was also wondering why hydrogen was talked about as a metal. I learned that because hydrogen takes on the nature of a metal in strong acids it is classified by that. Hydrogen also works as a reactant to tell if the metal is above or below hydrogen in the series.
In this chem talk I learned about Stoichiometry. A topic I have never heard of before. Stoichiometry has to deal with many different areas in Chemistry. First with moles which we have heard of before. One mole is equal to the molar mass, or atomic number of an atom. Stoichiometry has you complete equations and with this you have to deal with balancing equations something I have done before. Volume is also talked about in this section when gas has the same volume, which is 22.4 L, when it is standard temperature and pressure. Stoichiometry is the study of the relationships (mass-vol.) among substances involved in chemical reactions. When working with Stoichiometry equations you have to remember the little things like canceling out and always having the same unit at the end. I have prior knowledge with this as we worked with equations like this earlier in the year. Overall I learned much more about Stoichiometry and how it deals with the real world when new chemicals are found to cure different viruses including cancer.
This chem talk was about balancing equations. A balanced equation means that means that they are the same number of elements that are reactants as products. This is proven by the laws of conservation of matter, which states matter cannot be created or destroyed. This is shown in the real world when you take a log of wood and burn it. All the elemental atoms making up the molecular compounds of the wood will reform into other substances and various other different compounds plus heat energy. If all of these new substances could be collected, the log could not be reformed
The original matter has been changed into other forms and the log cannot be re-created. Balncing eqautions can also be applicable to balancing things in the real world including school life.
- Gases have full valence shells so that means they do not want to lose or gain electrons, the molecules in gasses are also very spread apart from each other which means there is little to no attraction.
- a. polar b. nonpolar c. nonpolar
- B, C, A
- The intermolecular forces in water are stronger than those in methane gas
In this chem talk we learned about Intermolecular forces and kinetic molecular motion. Intermolecular forces is the relation to the number and position of electrons. They have electrical charges, positive or negative. I learned the reason why solids have a definite shape and volume which are the properties of only solids is because of intermolecular forces. This chem talk also brought in new ideas of electronegativity and polarity. Electronegativity is the ability of an atom of an element to attract electrons in a chemical bond. Polarity is the difference of electronegativity of neighboring atoms which causes the electrons to be more attracted to one of the atoms in the bond making one of the atoms slightly negative and the other slightly positive. This chem talk brought in some ideas I have heard of and others I learned much more about.
In this chem talk we taled about lewis sturctures of aotms and molecules. Earlier in the year we talked about lewis structures. A lewis structure is a picture or diagram that shows the outer shell valence electron. You have to find out what row and type of metal they are on the periodic table in order to find out how many valence electrons. What i did learn from this seciton is that the atom with the most electorns tat don’t have a pair next to them is that atom that goes in the middle. We also learned about bonding and nonbonding which i had prior knoledge on.Shared pairs of electrons are cpvalent bonds and atoms with unshared pairs is calle dnonbonding or lone pair. Bonding can be seen by building a molecule visually. In class we didi this different building blocks. We understood when we built each molecule that they each have a shape and degree of angle. When you have lone pairs on the cento of the atom, the angles get smaller. This can be attributed to the pushing together of the atoms to become a pair, which ultimatly becomes smaller. In this chem talk I learned much more about bonds and how they are connected to shapes and angles which i found interesting.