Regents Chemistry Test Preparation Practice

    Separation Of The Components Of A Mixture

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    Base your answers to questions 10 on the information below and on your knowledge of chemistry.

    During a laboratory activity, appropriate safety equipment is used and safety procedures are followed. A student separates a sample of rock salt that has two components; NaCl(s) and small insoluble rock particles. First, the student thoroughly stirs the sample of rock salt into a sample of water in a fl ask. The mixture in the fl ask is fi ltered using the lab apparatus shown below.

    separation-of-the-components-of-a-mixture fig: chem12020-exam_g11.png

    The water is evaporated from the beaker. The fi lter paper and its contents are dried. The data collected by the student are shown in the table below.

    separation-of-the-components-of-a-mixture fig: chem12020-exam_g10.png

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    Base your answers to questions 11 on the information below and on your knowledge of chemistry.

    A hydrate is a compound that has water molecules within its crystal structure. Magnesium sulfate heptahydrate, MgSO4•7H2O, is a hydrated form of magnesium sulfate. The hydrated compound has 7 moles of H2O for each mole of MgSO4. When 5.06 grams of MgSO4•7H2O are heated to at least 300.°C in a crucible by using a laboratory burner, the water molecules are released. The sample was heated repeatedly, until the remaining MgSO4 had a constant mass of 2.47 grams. During this laboratory activity, appropriate safety equipment was used and safety procedures were followed.

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    Base your answers to questions 12 on the information below and on your knowledge of chemistry.

    Crude oil, primarily a mixture of hydrocarbons, is separated into useful components in a fractionating tower. At the bottom of the tower, the crude oil is heated to about 400°C. The gases formed rise and cool. Most of the gases condense and are collected as liquid fractions. The table below shows the temperature ranges for collecting various hydrocarbon fractions.

    hydrocarbons fig: chem12019-exam_g17.png

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    Base your answers to questions 13 on the information below and on your knowledge of chemistry.

    In a laboratory investigation, a student is given a sample that is a mixture of 3.0 grams of NaCl(s) and 4.0 grams of sand, which is mostly SiO2(s). The purpose of the investigation is to separate and recover the compounds in the sample. In the first step, the student places the sample in a 250-mL flask. Then, 50. grams of distilled water are added to the flask, and the contents are thoroughly stirred. The mixture in the flask is then filtered, using the equipment represented by the diagram below.

    solutions fig: chem12019-exam_g15.png

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