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3 years ago

Plz help thx...

Chemistry

2 answers:

Damm [24]3 years ago

7 0

1) For example, sodium oxide (Na₂O).

One one molecule of sodium oxide has one sodium atome (Na) and two oxygen atoms (O).

The subscript after element shows the number of elements in a molecule.

2) Yes, it possible for two different compounds to be made from the exact same two elements.

This are isomers, same molecular formula, but different arrangements of atoms.

For example, n-butane (C₄H₁₀) and 2-methylpropane (C₄H₁₀).

3) There are large number of compounds in this world, around 40 millions.

ArbitrLikvidat [17]3 years ago

4 0

Answer:

salt

Explanation:

sodium chloride. 1 sodium atom and one hydrogen atom.

It is possible because there could be more atoms, making it more or less reactant.

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A chemist adds of a sodium thiosulfate solution to a reaction flask. Calculate the mass in grams of sodium thiosulfate the chemi

schepotkina [342]

This is a incomplete question.The complete question is:

A chemist adds 180.0 ml of a 1.77 mol/L of sodium thiosulfate solution to a reaction flask. Calculate the mass in grams of sodium thiosulfate the chemist has added to the flask. Be sure your answer has the correct number of significant digits.

Answer: 50.4 g

Explanation:

To calculate the number of moles for given molarity, we use the equation:

$\text{Moles of solute}={\text{Molarity of the solution}}\times{\text{Volume of solution (in L)}}$ .....(1)

Molarity of sodium thiosulfate solution = 1.77 M

Volume of sodium thiosulfate solution = 180.0 mL = 0.1800 L

Putting values in equation 1, we get:

$\text{Moles of sodium thiosulfate}={1.77}\times{0.1800}=0.319moles$

Mass of sodium thiosulfate = $moles\times {\text {Molar mass}}=0.319moles\times 158.11g/mol=50.4g$

Thus 50.4 g of sodium thiosulfate the chemist has added to the flask.

6 0

3 years ago

The heat capacity of air is much smaller than that of water, and relatively modest amounts of heat are needed to change its temp

LekaFEV [45]

Answer:

$Q=9.2x10^5J$

$t=614s=10.2min$

Explanation:

Hello,

In this case, we can compute the energy by using the following formula for air:

$Q=nCp\Delta T$

Whereas the moles of air are computed via the ideal gas equation at room temperature inside the 5.5m x 6.5m x 3.0m-room:

$n=\frac{PV}{RT}\\\\V=5.5m*6.5m*3.0m=107.25m^3*\frac{1000L}{1m^3}=107250L\\ \\n=\frac{1atm*107250L}{0.082\frac{atm*L}{mol*K}*298.15K}\\ \\n=4386.8mol$

Now, we are able to compute heat, by considering that the temperature raise is given in degree Celsius or Kelvins as well:

$Q=4386.8mol*21\frac{K}{mol*K}*10K \\\\Q=9.2x10^5J$

Finally, we compute the time required for the heating by considering the heating rate and the required heat, shown below:

$t=\frac{9.2x10^5J}{1.5\frac{kJ}{s}*\frac{1000J}{1kJ} } \\\\t=614s=10.2min$

Regards.

8 0

3 years ago

Heat transferred by direct contact from one particle of matter to another is know as ____.

Alex777 [14]

Answer:

Explanation:

6 0

3 years ago

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A certain first-order reaction is 27.5 percent complete in 8.90 min at 25°C. What is its rate constant?

jeyben [28]

Answer:

$k= 0.145min^{-1}$

Explanation:

Hello there!

In this case, according to the given information, it turns out necessary for us remember that the first-order kinetics is given by:

$ln(A/A_0)=-kt$

Whereas the 27.5% complete means A/Ao=0.275, and thus, we solve for the rate constant as follows:

$k=\frac{ln(A/A_0)}{-t}$

Then, we plug in the variables to obtain:

$k=\frac{ln(0.275)}{-8.90min}\\\\k= 0.145min^{-1}$

Regards!

4 0

3 years ago

Do objects that give off light often give off heat?

pashok25 [27]

Answer:

Yes

Explanation:

Thermal radiation is emitted by any surface having a temperature higher than absolute zero. So the short answer to your question is yes. Light (electromagnetic radiation) of any frequency will heat surfaces that absorb it.

I hope it helps.

3 0

3 years ago

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