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3 years ago

Which can occur in a physical change? The mass can increase

1 answer:

3 0

In a physical change the form changes or the state of the matter. For instance water can freeze and water can melt, but it is still water.

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How many moles of copper are in 6,000,000 atoms of copper?

crimeas [40]

Answer: There will be 9.9632 × 10⁻¹⁸ moles of Copper in 6,000,000 atoms of Copper.

7 0

2 years ago

Consider 2 Al + 6 HCl → 2 AlCl3 + 3 H2 , the reaction of Al with HCl to produce hydrogen gas. What is the pressure of H2 if the

Margaret [11]

Answer : The pressure of hydrogen gas is 8.96 atm.

Explanation :

The given balanced chemical reaction is:

$2Al+6HCl\rightarrow 2AlCl_3+3H_2$

From the balanced chemical reaction we conclude that,

As, 2 moles of Al react to give 3 moles of $H_2$ gas

So, 4.50 moles of Al react to give $\frac{3}{2}\times 4.50=6.75$ moles of $H_2$ gas

Now we have to calculate the moles of $H_2$ gas when percent yield is 75.4.

$\text{The moles of }H_2=75.4\% \times 6.75=\frac{75.4}{100}\times 6.75=5.09moles$

Now we have to calculate the pressure of $H_2$ gas.

Using ideal gas equation :

PV = nRT

where,

P = Pressure of hydrogen gas = ?

V = Volume of the hydrogen gas = 14.0 L

n = number of moles of hydrogen gas = 5.09 moles

R = Gas constant = $0.0821L.atm/mol.K$

T = Temperature of hydrogen gas = 300 K

Putting values in above equation, we get:

$P\times 14.0L=5.09mol\times 0.0821L.atm/mol.K\times 300K\\\\P=8.96atm$

Therefore, the pressure of hydrogen gas is 8.96 atm.

3 0

2 years ago

Integrated rate law for second order unimolecular irreversible

kirill115 [55]

Answer:

The rate law for second order unimolecular irreversible reaction is

$\frac{1}{[A]} = k.t + \frac{1}{[A]_{0} }$

Explanation:

A second order unimolecular irreversible reaction is

2A → B

Thus the rate of the reaction is

$v = -\frac{1}{2}.\frac{d[A]}{dt} = k.[A]^{2}$

rearranging the ecuation

$-\frac{1}{2}.\frac{k}{dt} = \frac{[A]^{2}}{d[A]}$

Integrating between times 0 to <em>t </em>and between the concentrations of $[A]_{0}$ to <em>[A].</em>

$\int\limits^0_t -\frac{1}{2}.\frac{k}{dt} =\int\limits^A_{0} _A\frac{[A]^{2}}{d[A]}$

Solving the integral

$\frac{1}{[A]} = k.t + \frac{1}{[A]_{0} }$

5 0

3 years ago

The color of light emitted during a flame test depends on

tiny-mole [99]

option of d is the write answer

3 0

2 years ago

Read 2 more answers

gypsum is insoluble in water. you are asked to purify a sample of gypsum that is contaminated with a soluble salt.

katen-ka-za [31]

Answer:

a. The apparatus required to purify gypsum sample are: Bunsen burner, beaker, Filter Funnel, stirring rod, the filter paper.

b. Gypsum is a sulfate mineral that is made up of calcium sulfate dihydrate. Step-by-step instruction to purify gypsum sample is as follows:

1. Add water to the gypsum sample in a beaker.

2. Use the stirring rod to mix the mixture well.

3. Filter off the excess solid from the mixture using the filter paper and filter funnel.

4. Put the filtered mixture over the bunsen burner and evaporate the excess water from the mixture.

5. Allow the hot liquid to cool down and filter it again through the filter paper to get the pure gypsum.

7 0

3 years ago