Tutor profile: Erica S.
True or False? Electrons are positive.
False, electrons are negative. Atoms are made up of extremely small particles called protons, neutrons, and electrons. Protons and neutrons are in the center of the atom, making up the nucleus, while electrons surround the nucleus. Protons have a positive charge, neutrons have no charge, and electrons have a negative charge. The charge on the proton and electron are exactly the same size, just opposite. Because opposite charges attract, protons and electrons attract each other. It is important to understand this because electrons play a crucial role in other chemistry topics like redox reactions (chemical reactions in which both oxidation and reduction occur). For example, balancing out the following redox reaction, where the transfer of electrons is occurring: NaBr + CL2 --> NaCl + Br2 In these kinds of reactions, the substance which is reduced in the redox reaction is known as the oxidizing agent, while the substance which is oxidized in the redox reaction is known as the reducing agent. We know an equation is balanced if the number of each type of atom on both the reactant and product sides is equal. In this instance, we need to multiply NaBr (the reactant side) and NaCl (the product side) by 2 so that the number of each type of atom is equal. In the balanced form, the equation would look like: 2NaBr + Cl2 --> 2NaCl +Br2
The circulatory system is made up of blood vessels that carry blood away from and towards the heart. Which of the following blood vessels carries blood towards the heart? a. Arteries b. Veins c. The Aorta d. Capillaries
The correct answer is b. Veins Arteries (red) carry oxygen and nutrients away from your heart, to your body's tissues. Arteries begin with the aorta, the large artery leaving the heart. They carry oxygen- rich blood away from the heart and brand several times, becoming smaller and smaller as they carry blood further away from the heart. Veins (blue) are the blood vessels that take oxygen-poor blood back to the heart. Veins become larger and larger as they get closer to the heart. The superior vena cava is the large vein that brings blood from the head and arms to the heart, and the inferior vena cava brings blood from the abdomen and legs into the heart. Capillaries are small, thin blood vessels that connect the arteries and the veins. Their thin walls allow oxygen, nutrients, carbon dioxide, and waste products to pass to and from the tissue cells. So to think of it this way, arteries are red because the blood they carry is rich in oxygen- that is the blood the rest of your body's tissues need to properly function. Veins are blue because the blood they carry is poor in oxygen- it needs to be circulated back to the heart so the heart can pump it to your lungs, where it can then pick up oxygen and get rid of carbon dioxide.
Solve the system of equations. y = –3x + 4 x + 4y = –6
Being that both of these equations have two variables, x and y, you will essentially substitute in one of the equations for a variable in the other equation in order to find a solution for both. To explain, if you look at the equations, the first one already has y isolated. This will make it easier then to replace the value of y in the second equation with "-3x + 4." To demonstrate, the second equation will now look like this: x + 4(–3x +4) = –6 From here, you will begin to solve to isolate x. You will begin with the order of multiplication so the equation will now look like: x + –12x +16 = –6 From here, you will move the 16 over to further isolate x: x + –12x = – 22 The two x's can be added together so if you think of it as 1x + –12x, that will equal –11x So now the equation will look like –11x= –22 To get x alone, you will divide out –11: –11x/–11 = –22/ –11 For a final answer of x= 2 Now to find the value of y, you will plug in "2" anywhere it says x in the first equation So: y = –3(2) + 4 y= –6 + 4 y = –2 For a final answer of: x = 2, y = – 2 You are able to double check whether you are correct by substituting the values in the second equation and making sure the resulting equality is true!
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