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aliina [53]
3 years ago
10

Can anyone please suggest me a good and easy project topic for physics and chemistry. For class nine or ten students.Please plea

se please help me.​
Chemistry
1 answer:
dolphi86 [110]3 years ago
8 0
Volcano , bleach and fabuloso , flour and soap
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combustion analysis of a hydrocarbon produced 33.01g CO2 and 13.51g H2O. Calculate the empirical formula for the hydrocarbon
masya89 [10]

Answer:

\rm CH_2.

Explanation:

Carbon and hydrogen are the only two elements in a hydrocarbon. When a hydrocarbon combusts completely in excess oxygen, the products would be \rm CO_2 and \rm H_2O. The \rm C and \rm H would come from the hydrocarbon, while the \rm O atoms would come from oxygen.

Look up the relative atomic mass of these three elements on a modern periodic table:

  • \rm C: 12.011.
  • \rm H: 1.008.
  • \rm O: \rm 15.999.

Calculate the molar mass of \rm CO_2 and \rm H_2O:

M(\mathrm{CO_2}) = 12.011 + 2 \times 15.999 = 44.009\; \rm g \cdot mol^{-1}.

M(\mathrm{H_2O}) = 2 \times 1.008 + 15.999 = 18.015\; \rm g \cdot mol^{-1}

Calculate the number of moles of \rm CO_2 molecules in 33.01\; \rm g of \rm CO_2\!:

\displaystyle n(\mathrm{CO_2}) = \frac{m(\mathrm{CO_2})}{M(\mathrm{CO2})} = \frac{33.01\; \rm g}{44.009\; \rm g\cdot mol^{-1}} \approx 0.7501\; \rm mol.

Similarly, calculate the number of moles of \rm H_2O molecules in 13.51\; \rm g of \rm H_2O\!:

\displaystyle n(\mathrm{H_2O}) = \frac{m(\mathrm{H_2O})}{M(\mathrm{H_2O})} = \frac{13.51\; \rm g}{18.015\; \rm g\cdot mol^{-1}} \approx 0.7499\; \rm mol.

Note that there is one carbon atom in every \rm CO_2 molecule. Approximately0.7501\; \rm mol of \rm CO_2\! molecules would correspond to the same number of \rm C atoms. That is: n(\mathrm{C}) \approx 0.7501\; \rm mol.

On the other hand, there are two hydrogen atoms in every \rm H_2O molecule. approximately 0.7499\; \rm mol of \rm H_2O molecules would correspond to twice as many \rm H\! atoms. That is: n(\mathrm{H}) \approx 2 \times 0.7499 \; \rm mol\approx 1.500\; \rm mol.

The ratio between the two is: n(\mathrm{C}): n(\mathrm{H}) \approx 1:2.

The empirical formula of a compound gives the smallest whole-number ratio between the elements. For this hydrocarbon, the empirical formula would be \rm CH_2.

6 0
3 years ago
How many liters of oxygen gas, at standard temperature and pressure, will react with 25.0 grams of magnesium metal? Show all of
love history [14]
Given:
2 Mg + O2 → 2 MgO 
So,
<span>(25.0 g of Mg / 24.3051 g/mole) x (1/2) x (22.4 L/mole) = 11.5 L  of Oxygen will react with 25 grams of magnesium metal.</span>
8 0
3 years ago
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A scientist is researching the solar system. How can the scientist best add to existing empirical evidence about the solar syste
Bogdan [553]

Answer:

The correct option is;

c. The scientist can make and record observations

Explanation:

Empirical evidence are evidences obtained by direct observation, sensual perception or direct measurement. It is the processed and useful data gathered and stored in a material form or documented to provide record of the measurement.

With the aid of empirical evidence, it is possible for researchers to find answers to question regarding topics that can vastly impact every day life.

With empirical evidence, it is possible to determine the effects of treatment in a study such as the invention of working car safety devices such as seat belts and airbags.

7 0
3 years ago
Several bird species feed is a certain species of tree. Each bird species feeds in a different part of the tree. Which statement
Fofino [41]

Answer:

They have adapted to different niches.

Explanation:

due to competition

8 0
3 years ago
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What is happening to the protons in the nucleus and the number of orbits as you move across the periodic table from left to righ
baherus [9]

Explanation:

As you move across the periodic table, the number of protons and neutrons increases but the number of orbital levels of the period remains the same. The atomic radii therefore decrease, across the period, because the increase in proton number causes an increased pull of the orbital electrons bringing them closer to the nucleus.

As you move down a group in a periodic table, the number of orbital levels increase.  The effective nuclear charge of the nucleus of the atoms decreases due to the increased number of orbital levels that shield the valence electrons from the attractive force nucleus.

6 0
3 years ago
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