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2 years ago

3x - 12 = 7x + 8 -4x - 12 = 8 -4x - 20 X = -5

Chemistry

1 answer:

Dimas [21]2 years ago

3 0

Answer:

1.Set your equations Raquel to each other

2.given

3.subtract 7x from both sides

4. Add 12 to both sides

5.divide both sides by four and you get negative 5

Explanation:

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A student mixes 33.0 mL of 2.70 M Pb ( NO 3 ) 2 ( aq ) with 20.0 mL of 0.00157 M NaI ( aq ) . How many moles of PbI 2 ( s ) prec

GalinKa [24]

Answer: The moles of precipitate (lead (II) iodide) produced is $1.57\times 10^{-5}$ moles

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 lead (II) nitrate:

Molarity of lead (II) nitrate solution = 2.70 M

Volume of solution = 33.0 mL = 0.033 L (Conversion factor: 1 L = 1000 mL)

Putting values in equation 1, we get:

$2.70M=\frac{\text{Moles of lead (II) nitrate}}{0.033L}\\\\\text{Moles of lead (II) nitrate}=(2.70mol/L\times 0.0330L)=0.0891mol$

For NaI:

Molarity of NaI solution = 0.00157 M

Volume of solution = 20.0 mL = 0.020 L

Putting values in equation 1, we get:

$0.00157M=\frac{\text{Moles of NaI}}{0.020L}\\\\\text{Moles of NaI}=(0.00157mol/L\times 0.0200L)=3.14\times 10^{-5}mol$

For the given chemical reaction:

$Pb(NO_3)_2(aq.)+2NaI(aq.)\rightarrow PbI_2(s)+2NaNO_3(aq.)$

By Stoichiometry of the reaction:

2 moles of NaI reacts with 1 mole of lead (II) nitrate

So, $3.14\times 10^{-5}$ moles of NaI will react with = $\frac{1}{2}\times 3.14\times 10^{-5}=1.57\times 10^{-5}mol$ of lead (II) nitrate

As, given amount of lead (II) nitrate is more than the required amount. So, it is considered as an excess reagent.

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

By Stoichiometry of the reaction:

2 moles of NaI produces 1 mole of lead (II) iodide

So, $3.14\times 10^{-5}$ moles of NaI will produce = $\frac{1}{2}\times 3.14\times 10^{-5}=1.57\times 10^{-5}moles$ of lead (II) iodide

Hence, the moles of precipitate (lead (II) iodide) produced is $1.57\times 10^{-5}$ moles

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2 years ago

the temperature of a sample of water increases from 20celsius to 46.6celsius as it absorbs 5650 J of heat. what is the mass of t

Levart [38]

Answer:

m = 50.74 kg

Explanation:

We have,

Initial temperature of water is 20 degrees Celsius

Final temperature of water is 46.6 degrees Celsius

Heat absorbed is 5650 J

It is required to find the mass of the sample. The heat absorbed is given by the formula ad follows :

$Q=mc\Delta T$

c is specific heat of water, c = 4.186 J/g°C

So,

$m=\dfrac{Q}{c\Delta T}\\\\m=\dfrac{5650}{4.186\times (46.6-20)}\\\\m=50.74\ kg$

So, the mass of the sample is 50.74 kg.

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3 years ago

Which statement describes a system that consists of sugar crystals dissolving in water?

trapecia [35]

To know the answer, you either know what is really the nature and chemistry of a sugar solution. You can also know the answer by knowing the meaning of entropy. Entropy is often interpreted as the degree of disorder or randomness in the system. So the correct statement is that the system becomes more disordered and has an increase in entropy.

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3 years ago

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Equal masses of water undergo condensation, deposition, evaporation, and sublimation. a) Which process releases the most energy?

Artemon [7]

Answer:

A. Condensation

B. Evaporation

Explanation:

Condensation releases energy when water vapor condenses to form water droplets. Evaporation absorbs energy whenever it changes from liquid to gas, the heat from the sun heats the water up and absorbs energy.

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Which of the following is true about homogeous mixtures

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