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gladu [14]
3 years ago
11

Write the symbol for every chemical element that has atomic number greater than 55 and atomic mass less than 144.0 u

Chemistry
1 answer:
laila [671]3 years ago
3 0
You will need a periodic table to help you answer this problem. The atomic numbers are arrange from lowest to highest in the periodic table. You can locate element number 55 to be Cesium with an atomic weight of 132.905 amu. So, you start from element 56. The following elements are:

56     Barium       137.328 amu
57     Lanthanium   138.905 amu
58     Cerium       140.116 amu
59     <span>Praseodymium    140.908 amu
60     Neodymium   144.243 amu

Neodymium is already greater than 144 amu. Therefore, these elements only include Barium, Lanthanium, Cerium and Praseodymium.</span>
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A regular solid measures 13.4 cm x 11.0 cm x 2.2cm. Calculate the volume of the solid.
AlekseyPX

Answer:

324.28 cm cubed

Explanation:

13.4 cm x 11.0cm x 2.2cm = 324.28 cm cubed

7 0
3 years ago
John dalton said that all atoms are identical in size and mass. explain why this is incorrect.
andrew11 [14]
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4 0
3 years ago
Glycerol (C3H8O3), also called glycerine, is widely used in the food and pharmaceutical industries. Glycerol is polar and dissol
Stells [14]

Here is the complete question.

Glycerol (C3H8O3), also called glycerine, is widely used in the food and pharmaceutical industries. Glycerol is polar and dissolves readily in water and polar organic solvents like ethanol. Calculate the mole fraction of the solvent in a solution that contains 1.61 g glycerol dissolved in 22.60 mL ethanol (CH3CH2OH; density = 0.7893 g/mol). Round to four significant digits

Answer:

0.9567 mol

Explanation:

Given that:

mass of glycerol = 1.61 g

molar mass of glycerol = 92.1 g/mol

no of mole = \frac{mass}{molar mass}

∴ number of moles of glycerol (n_{glycerol}) = \frac{1.61}{92.1}

= 0.0175 mol

Volume of ethanol = 22.60 mL

Density of ethanol = 0.7893 g/mL

Since Density = \frac{mass}{volume}

∴  mass of ethanol = density of ethanol × volume of ethanol

mass of ethanol =  0.7893 g/mL × 22.60 mL

mass of ethanol =  17.838 g

Number of moles of ethanol (n_{ethanol}) = \frac{17.838}{46.0684}

= 0.387 mole

∴ the mole fraction of the solvent can be determined as:

X_{solvent} = X_{ethanol} = \frac{n_{ethanol}}{n_{glycerol}+n_{ethanol}}

=\frac{0.387 mol}{(0.0175+0.387)mol}

= \frac{0.387mol}{0.4045mol}

= 0.95673671199

≅ 0.9567 mol

∴ The mole fraction of the solvent in a solution that contains 1.61 g glycerol dissolved in 22.60 mL ethanol is = 0.9567 mol

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4 years ago
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