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3 years ago

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Chemistry

2 answers:

devlian [24]3 years ago

4 0

Answer:

Explanation:

violet light has the shortest wavelength

Lelu [443]3 years ago

3 0

The answer is D. In the visible spectrum of light, ultraviolet light has the most energy while red has the least energy. Violet light has shorter wavelengths and higher frequency. This is converse to red light that has longer wavelengths but lower frequency.

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A 5.000 g mixture contains strontium nitrate and potassium bromide. Excess lead(II) nitrate solution is added to precipitate out

scZoUnD [109]

Answer: The mass percent of potassium bromide in the mixture is 9.996%

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

For lead (II) bromide:

Given mass of lead (II) bromide = 0.7822 g

Molar mass of lead (II) bromide = 367 g/mol

Putting values in equation 1, we get:

$\text{Moles of lead (II) bromide}=\frac{0.7822g}{367g/mol}=0.0021mol$

The chemical equation for the reaction of lead (II) nitrate and potassium bromide follows:

$2KBr+Pb(NO_3)_2\rightarrow PbBr_2+2KNO_3$

By Stoichiometry of the reaction:

1 mole of lead (II) bromide is produced from 2 moles of potassium bromide

So, 0.0021 moles of lead (II) bromide will be produced from = $\frac{2}{1}\times 0.0021=0.0042mol$ of potassium bromide

Now, calculating the mass of potassium bromide by using equation 1, we get:

Molar mass of KBr = 119 g/mol

Moles of KBr = 0.0042 moles

Putting values in equation 1, we get:

$0.0042mol=\frac{\text{Mass of KBr}}{119g/mol}\\\\\text{Mass of KBr}=0.4998g$

To calculate the percentage composition of KBr in the mixture, we use the equation:

$\%\text{ composition of KBr}=\frac{\text{Mass of KBr}}{\text{Mass of mixture}}\times 100$

Mass of mixture = 5.000 g

Mass of KBr = 0.4998 g

Putting values in above equation, we get:

$\%\text{ composition of KBr}=\frac{0.4998g}{5.000g}\times 100=9.996\%$

Hence, the percent by mass of KBr in the mixture is 9.996 %

5 0

3 years ago

If the internal energy of a system increases but there is no change in temperature, then the system's energy is increasing.

777dan777 [17]

Answer:

kintic

Explanation:

4 0

3 years ago

Read 2 more answers

Explain, in terms of element classification, why KBr is an ionic compound

enot [183]

LBr is ionic compound because k for potassium is metal which means it’s on the left side of the periodic table and Br which is bromine is a non metal which means is on the right side of the periodic table.

In Conclusion when a non metal and metal come together the are called ionic compound

5 0

3 years ago

Trimix is a general name for a type of gas blend used by technical divers and contains nitrogen, oxygen and helium. In one Trimi

Keith_Richards [23]

Answer:

28.2

Explanation:

Add all of the pressures, 55, 90, and 50, and divide 100 by the answer you get (195). You'll get 0.512820513 and multiply it by .55 (atm of Oxygen) and you'll get 28.2

6 0

3 years ago

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57. A recipe for s'mores calls for 2 graham crackers, 2 chocolate pieces and 1 marshmallow. If I

geniusboy [140]

Answer:Noble gases:

are highly reactive.

react only with other gases.

do not appear in the periodic table.

are not very reactive with other elements.

Explanation:Noble gases:

are highly reactive.

react only with other gases.

do not appear in the periodic table.

are not very reactive with other elements.

5 0

2 years ago