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Chemistry, 04.05.2021 04:20 gracelong4326
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Chemistry, 22.06.2019 11:40, Wemaybewrong
Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)
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Chemistry, 22.06.2019 18:10, ellemarshall13
Measurements that have similar values are: a. usually accurate b. sometimes accurate c. always accurate d. never accurate
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Chemistry, 23.06.2019 08:50, carlinryan
Why are enzymes important to cells? they bring about chemical reactions. they provide structural support. they form the two layers of membranes. they store large quantities of energy.
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