For this problem, assume that water consistsonly of the most abundant isotopes of oxygen ( 16 O and 18 O ). Theatomic mass for 16 O is 15.9949146 u, and the atomic mass for 18 O is 17.99916 10 u. (a) A standard seawater sample contains 0.1995% 18 O . Calculate the atomic weight of oxygen in seawater, and report youranswer to five decimal places. (b) A polar ice core sample contains 0.1971% 18 O . Calculate theatomic weight of oxygen in polar ice, and report your answerto five decimal places.
For this problem, assume that water consistsonly of the most abundant isotopes of oxygen ( 16 O and 18 O ). Theatomic mass for 16 O is 15.9949146 u, and the atomic mass for 18 O is 17.99916 10 u. (a) A standard seawater sample contains 0.1995% 18 O . Calculate the atomic weight of oxygen in seawater, and report youranswer to five decimal places. (b) A polar ice core sample contains 0.1971% 18 O . Calculate theatomic weight of oxygen in polar ice, and report your answerto five decimal places.
Solution Summary: The author explains that the atomic weight of oxygen in seawater is to be calculated.
For this problem, assume that water consistsonly of the most abundant isotopes of oxygen (
16
O
and
18
O
). Theatomic mass for
16
O
is 15.9949146 u, and the atomic mass for
18
O
is 17.99916 10 u. (a) A standard seawater sample contains 0.1995%
18
O
. Calculate the atomic weight of oxygen in seawater, and report youranswer to five decimal places. (b) A polar ice core sample contains 0.1971%
18
O
. Calculate theatomic weight of oxygen in polar ice, and report your answerto five decimal places.
Phosphorus trichloride is important in the manufacture of insecticides, fuel additives, and flame retardants. Phosphorushas only one naturally occurring isotope, ³¹P, whereas chlorinehas two, ³⁵Cl (75%) and ³⁷Cl (25%). (a) What different molecu-lar masses (amu) can be found for PCl₃? (b) Which is the mostabundant? (c) What is the ratio of the effusion rates of the heavi-est and the lightest PCl₃ molecules?
In 1961, scientists agreed that the atomic mass unit (amu)would be defined as the mass of an atom of 12C. Before then,it was defined as the average mass of an atom of naturally occurring oxygen (a mixture of 16O, 17O, and 18O). The current atomic mass of oxygen is 15.9994 amu. (a) Did Avogadro’snumber change after the definition of an amu changed and, if so,in what direction? (b) Did the definition of the mole change?(c) Did the mass of a mole of a substance change? (d) Before1961, was Avogadro’s number 6.021023(when considered tothree significant figures), as it is today?
A gaseous binary compound has a vapor density that is 1.94 times that of oxygen at the same temperature and pressure. When 1.39 g of the gas is burned in an excess of oxygen, 1.21 g water is formed, removing all the hydrogen originally present.(a) Estimate the molecular mass of the gaseous compound.(b) How many hydrogen atoms are there in a molecule ofthe compound?(c) What is the maximum possible value of the atomicmass of the second element in the compound?(d) Are other values possible for the atomic mass of thesecond element? Use a table of atomic masses to identify the element that best fits the data.(e) What is the molecular formula of the compound?
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