Master Chemistry with Fun Quizzes & Brain Teasers!

Sarah and Keith are making candy for a holiday party and begin to argue about whether the melting sugar is a chemical or physical change. Keith says his teacher, Ms. Ortega, said physical changes are only a change in the state of matter, not a change in the chemicals that make up the material. Sarah argues that melting sugar is a change in the chemical makeup of the sugar because it doesn't look like sugar anymore. Who is right?
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Predict the growth mode for the following systems based on the surface tension data provided in the class note. Please explain briefly. a. Ni on Si substrate b. GaAs on Si substrate c. SiO2 on Si substrate d. SiO2 on NaCl substrate
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Solid Ca reacts with N2 gas to form solid calcium nitride, Ca3N2. a. A reaction mixture initially contains only calcium and nitrogen. When the reaction stops, the mixture contains 6 mol calcium, 4 mol nitrogen, and 12 mol calcium nitride. How many moles of calcium and nitrogen were present before the reaction began
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Compound Z has a MW of 100 g/mol. Your lab partner weighed 25 grams of compound Z and dissolved it in water to a final volume of 1 liter. What is the concentration of the solution expressed as a percentage by weight (w/v)
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_________would result in a shift the hemoglobin-oxygen dissociation curve to the right. Select the correct statement(s) to fill in the blank. a. An increase in PCO2 b. An increase in temperature c. An increase in pH d. (a) and (b) are correct; (c) is incorrect e. (a), (b), and (c) are all correct
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