CHM 1046 L Midterm review exam questions with 100% verified answers pass guaranteed

what is the purpose of today's lab? (Lab: analysis of copper in brass sample) - correct answers to calculate the percentage of copper present in a brass sample by using a spectrophotometer. what type of elements can you find in a brass sample?(Lab: analysis of copper in brass sample) - correct answers tin, lead, copper and zinc How is the concentration of copper (II) ions going to be determined in today's experiment? (Lab: analysis of copper in brass sample) - correct answers the molarity of Cu"^^ present will be deter mined spectrophotometrically using the Bausch & Lomb Spectronic 20. Define Molarity. What is the formula for Molarity? (Lab: analysis of copper in brass sample) - correct answers M= mol/volume in Liters Molarity measures the concentration of a given substance. It consists of the amount of moles divided by the volume of the solution given in liters. What is the wavelength that you will be using to measure the absorption of Cu2+ ions? - correct answers 620 micrometers (electromagnetic waves) What is the purpose of today's experiment? Do not just state the title of the experiment but try to explain in your own words what you will be doing in today's lab (Lab: intro. to qual. analysis: CATIONS) - correct answers The purpose is to test our observational skills when working with elements in reactions and identifying which solutions are which by testing their solubility and reactivity. Why are confirmatory tests necessary in identifying ions? (Lab: intro. to qual. analysis: CATIONS) - correct answers They help distinguish between cations/anions that have similar chemical properties. How would you separate Pb2+ from Fe3+? (Lab: intro. to qual. analysis: CATIONS) - correct answers By adding HCl-, a precipitate forms. The precipitate is PbCl2+. Mention at least 5 cations that you will be identifying in today's experiment? Do not forget to include their charges.(Lab: intro. to qual. analysis: CATIONS) - correct answers Na+ (sodium), NH4+(ammonium) ,Ag+(silver), Fe3+ (iron 3) and Al3+ (aluminum) It is now time to test your unknown solution and you observe that it happens to be colorless. What conclusion can you make from this observation? (Lab: intro. to qual. analysis: CATIONS) - correct answers if colorless, then the cations that would present color are absent. They should be Cr3+,Fe3+ and Ni2+ What is the purpose of today's experiment? (Lab: intro. to qual. analysis: ANIONS) - correct answers The purpose of the experiment is to analyze the behavior of the unknown salt as it undergoes a test with H2SO4- and to identify which of the six anions is in it. Name the ions involved in today's experiment? (Lab: intro. to qual. analysis: ANIONS) - correct answers SO4 2-, NO3-, Cl-, Br-, I- and CO3 2-. Their names are sulfate, nitrate, chloride, bromide, iodide, and carbonate. What is the first test you will perform on the solid ions? (Lab: intro. to qual. analysis: ANIONS) - correct answers concentrated sulfuric acid (H2SO4) test at room temp. If you had a mixture of potassium carbonate (K2CO3) and sodium iodide (NaI) in a sample, would the sulfuric acid test help you determine the presence of any of those anions? If so, what results would you expect to see while performing the experiment? (Lab: intro. to qual. analysis: ANIONS) - correct answers for co3 -2, there's no reaction. for the iodide, it results in a rotten egg smell and brown gas or violet color. What is the correct and safe way of smelling chemicals in a laboratory? (Lab: intro. to qual. analysis: ANIONS) - correct answers you should start off by wearing the proper lab safety attire, placing the test tube away from your face and bringing it up and gently wafting the air around the test tube so that you are able to smell the odor in the chemical but do not harm yourself. What is the purpose of today's experiment? (Lab: freezing point depression) - correct answers To use the concept of freezing point depression to determine the molar mass of an unknown compound by determination of the freezing point of a pure solvent and a solution. Solutions are homogenous mixtures that contain two or more components. What is the major component of the solution called? What is the minor component of the solution called? (Lab: freezing point depression) - correct answers The major component is called the solvent and the minor component is called the solute. Give at least 2 examples of colligative properties (Lab: freezing point depression) - correct answers boiling point and freezing point What is the definition of a nonvolative solute? (Lab: freezing point depression) - correct answers a nonvolatile solution has no measurable vapor pressure. True or False: The dissolution of a volatile solute in a solvent lowers the vapor pressure of the solvent, which in turn lowers the boiling point and raises the freezing the point. (Lab: freezing point depression) - correct answers False