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3 years ago

What is wrong with the following explanation of an experiment? When it was heated, the sample of carbon decomposed.

1 answer:

7 0

"Carbon" is an element. It is found in the fourth group of the periodic table, and it is a stable element. This means that it can not be decomposed via heating, because if an element were to break down, it would release its subatomic particles. The explanation was probably one used to describe the thermal decomposition of a compound into smaller compounds.

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Which formula represents an ionic compound?

kumpel [21]

When 2 elements are combined it creates an ionic compound

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3 years ago

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Pure research becomes ___ when scientists develop a hypothesis based on the data and try to solve a specific problem

Inessa05 [86]

Answer:

The answer is applied research

Explanation:

Pure research becomes applied research when scientists develop a hypothesis based on the data and try to solve a specific problem.

This is because the pure research try to understand, predict or explain the behavior of different phenomena (the data) while the applied research try to develop new technologies or methods (hypothesis) to take part, intervene and/or create changes on these phenomena and solve a specific problem.

5 0

3 years ago

How many moles, kmols in: 100 g of CO2, 1 litre of ethyl alcohol of density 0.789 g/cm3 and a) 1.5m3 of O2 at 25°C and 1 atm. b)

Nutka1998 [239]

Explanation:

1) Mass of carbon dioxide = 100 g

Molar mass of carbon dioxide = 44 g/mol

Moles of carbon dioxide = $\frac{100 g}{44 g/mol}=2.273 moles$

1 mol = 0.001 kmol

2.273 moles= 2.273 × 0.001 kmol = $2.273\times 10^{-3} kmol$

2) 1 liter of ethyl alcohol of density $0.789 g/cm^3$

Volume of ethyl alcohol ,V= 1 L = 1000 mL

Density of ethyl alcohol =d = $0.789 g/cm^3$

$1 cm^3=1 mL$

Mass of ethyl alcohol = m

$m=d\times V=0.789 g/cm^3\times 1000 mL=789 g$

Molar mass of ethyl alcohol = 46 g/mol

Moles of ethyl alcohol = $\frac{789 g}{46 g/mol}=17.152 mol$

$17.152 mol=17.152\times 0.001 kmol=1.7152\times 10^{-4} kmol$

3) Volume of oxygen gas,V = $1.5 m^3=1500 L$

$1 m^3= 1000 L$

Temperature of the gas = T= 25°C = 298.15 K

Pressure of the gas ,P= 1 atm

Moles of oxygen gas = n

$PV=nRT$

$n=\frac{RT}{PV}=\frac{0.0821 atm L/mol K\times 298.15 K}{1 atm\times 1500 L}=0.01632 mol$

0.01632 mol = 0.01632 × 0.001 kmol= $1.632\times 10^{-5} kmol$

4) Volume water in mixture = 1 L

Density of water = $1000 kg/m^3=\frac{1,000,000 g}{1000 L}=1000 g/L$

Mass of water = $1000 g/L\times 1 L = 1000 g$

Volume of alcohol = 2.5 L

Density of alcohol = $789 kg/m^3=\frac{789000 g}{1000 L}=789 g/L$

Mass of alcohol = $789 g/L\times 2.5 L = 1972.5 g$

Mass of mixture = 1000 g + 1972.5 g = 2972.5 g

Mass percentage of water :

$\frac{1000 g}{2972.5 g}\times 100=33.64\%$

Mass percentage of alcohol :

$\frac{1972.5 g}{2972.5 g}\times 100=66.36\%$

Moles of water :

$n_1=\frac{1000 g}{18 g/mol}=55.55 mol$

Moles of alcohol =

$n_2=\frac{1972.5 g}{46 g/mol}=42.88 mol$

Mole fraction of water :

$\chi_1=\frac{n_1}{n_1+n_2}=\frac{55.55 mol}{55.55 mol+42.88 mol}=0.5644$

Mole fraction of alcohol :

$\chi_2=\frac{n_2}{n_1+n_2}=\frac{42.88 mol}{55.55 mol+42.88 mol}=0.4356$

3 0

3 years ago

Why do you think it would be important for scientists to test local water?

il63 [147K]

Answer:

To see if the water is safe to drink.

Explanation:

It is important for local water to be tested to see how the water quality is and to check if there are any pollutants (such as fertilizers or oil). Most of the world's water is not safe to consume, it would be useful to know what your local water is like.

4 0

3 years ago

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What precautions must be taken when you introduce a mixture of compounds to be separated onto a liquid chromatography column?

earnstyle [38]

The slim exit of the column is first persisted with glass wool or a permeable plate in order to sustain the column packing element and keep it from getting out of the tube. Then the adsorbent solid, which is usually a silica, is firmly packed into the glass tube to make the separating column. The packing of the non-moving phase into the glass column must be done with precaution to create an even distribution of material. An even distribution of adsorbent material is very important to lessen the existence of air bubbles and/or channels inside the column. To finish preparing the column, the solvent to be used as the mobile phase is delivered through the dry column. Then the column is said to be "wetted" and the column must stay wet throughout the entire procedure. Once the column is properly prepared, the sample to be separated is placed at the top of the wet column.

5 0

3 years ago