Usually, the decision about whether or not to use scientific notation is up to you. An answer of 1.2×103 is equivalent in EVERY WAY to 1200. Thus, you can answer either way. But be sure to check to see if the question states how the answer needs to be given. There is one condition under which scientific notation MUST...
Dishwashing liquid formulations have changed over time, making it difficult to find one which contains sodium stearate. This experiment can still be completed with the assumption that the dish soap contains a theoretical sodium stearate concentration. It will work regardless, with the difference that in the end, the mo...
You learned how to determine the chemical formula of an ionic compound (salt) in Module 4 (pp. 137-145). You then learned it again when you were taught how to do it for ionic compounds that contain polyatomic ions in Module 5 (pp. 175-180). Review those sections, and you will be able to determine the chemical formula...
Don’t get confused here. Hess did not DISCOVER that elements in their elemental form have zero enthalpy. He DEFINED it to be that way. Remember, we have no way of measuring the absolute enthalpy of a substance. Thus, there is no way he could have discovered this. Instead, he said that since all we can do is measure the...
Once you know the mass in amu, you also know how many grams it takes to make a mole. Remember, the mass on the periodic chart tells you two things: 1) The mass in amu 2) The number of grams it takes to make a mole. When you figure out the mass from the periodic chart, you will find that it is 295.3. That tells you...
Students can enroll in the [ Significant Figures and Precision ][1]Self-Paced Course taught by Live Classes teacher, Mr. Dan Martin. [1]: https://online.apologia.com/courses/significant-figures-precision-self-paced ...
The electronegativity does change across the periodic chart as well as up and down. However, if you move along the chart correctly, you can find atoms that have the same electronegativities. Iodine and sulfur, for example, have the same electronegativity. If you start at Iodine and move up, you are increasing electro...
You have to remember that the rules for addition and subtraction are totally different than the rules for multiplication and division (see pp. 25-26). In addition and subtraction, you DO NOT count significant figures. Yes, each of those numbers has two significant figures, but that is not relevant to addition and subtr...
Although this is up to each individual teacher, we recommend that you allow your students to use the periodic table of elements (provided in Module 2) during their tests, along with a calculator, pencil, and some paper. ...
The answer is "Na" because, of the elements listed, sodium is the furthest left on the periodic table of elements. To look at the science behind this, please refer to pages 145-148 of the Chemistry 3rd Edition textbook. ...