The charge on the manganese in the salt MnF3 ? +1 -1 -2 +3 +2 Aluminum reacts wi
ID: 859965 • Letter: T
Question
The charge on the manganese in the salt MnF3 ? +1 -1 -2 +3 +2 Aluminum reacts with a certain nonmetallic element to form a compound with the general formula ALX. Element X is a diatomic gas at room temperature. Element X must be . oxygen fluoride chlorine nitrogen sulfur The correct name of MgCl2 is ? magnesium dichloride magnesium chloride magnesium chlorine magnesium chlorate magnesium perchlorate Which of the following compounds is chromium (III) oxide? Cr2O3 CrO3 Cr3O2 Cr3O Cr2O4 The formula of the carbonate ion is ? CO2 2- CO3 2- CO3 3- CO2 2- CO- Element X has three naturally occurring isotopes. The mass (amu) and % abundance of the isotopes are 37.9119 (5.07%), 39.017 (15.35%), and 42.111 (79.58%). What is the average atomic mass (amu) of element X?Explanation / Answer
6) E (+3)
7) D (nitrogen)
8) B (magnesium chloride)
The first person to answer this is wrong, # 8 is NOT magnesium dichloride. With ionic compounds (a metal and nonmetal together) you never use the numerical prefixes in the name. The prefixes are only used in covalent molecules (two or more nonmetals together)
9) A (Cr2O3)
10) B (CO3^-2)
11) Take the mass (amu) and multipy by the % abundance (as a fraction), and then add them all together:
(37.919)(0.507) + (39.017)(0.1535) + (42.111)(0.7958) = 58.726 amu
11) amu of Element X = 58.726 amu
If you need to identify element X, then Element X = Nickel (Ni)
The first person to answer # 11 is wrong. They did not convert the % abundances into fractions, which you must do in order to obtain the correct answer. In other words, they incorrectly divided the all numbers (including the given amu's) by 100, when only the % abundances should be divided by 100.
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