Chemistry, 22.11.2019 16:31 angelina12386

Combustion analysis of an unknown compound provides the following data: 73.5 grams c, 4.20 grams h, and 72.3 grams cl. what is the percent composition of each element in this compound?

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Answer from: needhelpwithHW10

Cl = 49.0%, H = 2.8% and Cl = 48.2%

Explanation: Masses of C, H and Cl elements are given and the question asks to calculate the percent composition of each element in the compound.

The formula used for percent composition that is mass percentage is:

mass percent of an element = $(\frac{element mass}{compound mass})*100$

Given:

mass of C = 73.5 grams

mass of H = 4.20 grams

mass of Cl = 72.3 grams

Mass of compound = 73.5 grams + 4.20 grams + 72.3 grams = 150 grams

percent composition of C = $(\frac{73.5}{150})*100$ = 49.0%

percent composition of H = $(\frac{4.20}{150})*100$ = 2.8%

percent composition of Cl = $(\frac{72.3}{150})*100$ = 48.2%

So, the compound has 49.0% C, 2.8% H and 48.2% Cl.

Answer from: Quest

The answer is b i think

Answer from: Quest

assuming that your periodic table has eighteen columns, you should highlight the four elements in the third column from the left of the table.

explanation

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the $3d$ have energy higher than those in the $4 s$ orbital while lower than those of the $4 p$ orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the $4s$ orbital is therefore filled right after $3p$ orbitals and before $3 d$ orbitals.

potassium has electron configuration $[\text{ar}] 4 s^{1}$ and calcium $[\text{ar}] 4 s^{2}$ . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration $[\text{ar}] 4 s^{2} \; 3d^{1}$ and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the $ns^{2} \; (n-1) p^{1}$ and should be highlighted as well.

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Combustion analysis of an unknown compound provides the following data: 73.5 grams c, 4.20 grams h,...

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