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3 years ago

Please help! brainliest, rattings, thanks, etc.

Chemistry

1 answer:

pochemuha3 years ago

3 0

According to Newton's first law of motion, it takes an unbalanced force to move an object at rest.

I hope this helps :)

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Iridium is a component of cosmic dust that rains down upon the earth at a constant rate. Why did Luis Alvarez suggest measuring

weqwewe [10]

Answer:

In order to determine the rate at which the sediment layers were deposited

Explanation:

Iridium is an important element that belongs to the Platinum group and they are dominantly present in the asteroids and comets. They are the key evidence that suggests the occurrence of an asteroidal impact or a mass extinction event that has taken place in the geological past.

The presence of Iridium mixed with the clay sediments in the boundary between the Cretaceous and Tertiary (K-T boundary) suggested the mass extinction event that wiped out numerous life forms from the earth.

The famous scientist Dr. Luis Walter Alvarez suggested measuring the concentration of Iridium in this K-T boundary in order to determine the rate at which these sediment layers were deposited. They were able to determine that these Iridium elements were present due to the asteroid impact on earth, that wiped out the dinosaurs from the earth. They also considered that this element can be produced from the eruptions of volcanoes.

6 0

3 years ago

Read 2 more answers

Is evaporation of water a physical change or a chemical change? explain your answer?

Olin [163]

Chemical because it would be impossible to get the evaporated water and turn it back into it's original substance.

8 0

3 years ago

What change in volume results if 60 mL of a gas is cooled from 33 C to 5 C?

Eva8 [605]

Answer:

Change in volume on changing temperature from 33 $^{\circ}C$ to 5 $^{\circ}C$ is 5.49 mL

Explanation:

Initial volume of gas = V = 60 mL

Assuming final volume of gas to be V' mL

Initial temperature = T = 33 $^{\circ}C$ = 306 K

Final temperature = T' = 5 $^{\circ}C$ = 278 K

The relationship between volume and temperature of gas at constant pressure is shown below

$\displaystyle \frac{V}{V'}=\displaystyle \frac{T}{T'} \\\displaystyle \frac{60\textrm{ mL}}{V'} = \displaystyle \frac{306\textrm{ K}}{T} \\V' = 54.51 \textrm{ mL} \\\textrm{Change in volume} = \left ( V-V' \right ) \\\textrm{Change in volume} = \left ( 60-54.51 \right )\textrm{ mL} \\\textrm{Change in volume} = 5.49 \textrm{ mL}$

Change in volume on changing temperature = 5.49 mL

6 0

2 years ago

A student reacts 20.0 mL of 0.248 M H2SO4 with 15.0 mL of 0.195 M NaOH. Write a balanced chemical equation to show this reaction

Molodets [167]

Answer: The concentration of salt (sodium sulfate), sulfuric acid and NaOH in the solution is 0.0418 M, 0.0999 M and 0 M respectively.

Explanation:

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

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

For NaOH:

Initial molarity of NaOH solution = 0.195 M

Volume of solution = 15.0 mL = 0.015 L (Conversion factor: 1 L = 1000 mL)

Putting values in equation 1, we get:

$0.195M=\frac{\text{Moles of NaOH}}{0.015L}\\\\\text{Moles of NaOH}=(0.195mol/L\times 0.015L)=2.925\times 10^{-3}mol$

For sulfuric acid:

Initial molarity of sulfuric acid solution = 0.248 M

Volume of solution = 20.0 mL = 0.020 L

Putting values in equation 1, we get:

$0.248M=\frac{\text{Moles of }H_2SO_4}{0.020L}\\\\\text{Moles of }H_2SO_4=(0.248mol/L\times 0.020L)=4.96\times 10^{-3}mol$

The chemical equation for the reaction of NaOH and sulfuric acid follows:

$2NaOH+H_2SO_4\rightarrow Na_2SO_4+2H_2O$

By Stoichiometry of the reaction:

2 moles of NaOH reacts with 1 mole of sulfuric acid

So, $2.925\times 10^{-3}$ moles of KOH will react with = $\frac{1}{2}\times 2.925\times 10^{-3}=1.462\times 10^{-3}mol$ of sulfuric acid

As, given amount of sulfuric acid is more than the required amount. So, it is considered as an excess reagent.

Thus, NaOH is considered as a limiting reagent because it limits the formation of product.

Excess moles of sulfuric acid = $(4.96-1.462)\times 10^{-3}=3.498\times 10^{-3}mol$

By Stoichiometry of the reaction:

2 moles of KOH produces 1 mole of sodium sulfate

So, $2.925\times 10^{-3}$ moles of KOH will produce = $\frac{1}{2}\times 2.925\times 10^{-3}=1.462\times 10^{-3}mol$ of sodium sulfate

For sodium sulfate:

Moles of sodium sulfate = $1.462\times 10^{-3}moles$

Volume of solution = [15.0 + 20.0] = 35.0 mL = 0.035 L

Putting values in equation 1, we get:

$\text{Molarity of sodium sulfate}=\frac{1.462\times 10^{-3}}{0.035}=0.0418M$

For sulfuric acid:

Moles of excess sulfuric acid = $3.498\times 10^{-3}mol$

Volume of solution = [15.0 + 20.0] = 35.0 mL = 0.035 L

Putting values in equation 1, we get:

$\text{Molarity of sulfuric acid}=\frac{3.498\times 10^{-3}}{0.035}=0.0999M$

For NaOH:

Moles of NaOH remained = 0 moles

Volume of solution = [15.0 + 20.0] = 35.0 mL = 0.035 L

Putting values in equation 1, we get:

$\text{Molarity of NaOH}=\frac{0}{0.050}=0M$

Hence, the concentration of salt (sodium sulfate), sulfuric acid and NaOH in the solution is 0.0418 M, 0.0999 M and 0 M respectively.

8 0

3 years ago

How many molecules of CrCl₃ are produced when 2.89 moles of CuCl₂ react? * 2Cr+3CuCI2-2CrCI3+3Cu

juin [17]

Explanation:

The reaction is CaCO

+2HCl→CaCl

O+CO

Thus, 2 moles of HCl reacts with one mole of calcium carbonate to produce one mole each of calcium chloride, water and carbon dioxide respectively.

Hence, 3 moles of HCl will react with excess of calcium carbonate to produce 3×

=1.5 mol of carbon dioxide

3 0

2 years ago