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3 years ago

PLEASE HELP THANKS

Chemistry

2 answers:

Dafna1 [17]3 years ago

8 0

Answer:

The answer is: A. 45 degrees Celsius

Explanation:

Answer:

In order to solve this problem, you need to know that an exothermic reaction is a chemical reaction that releases energy through light or heat to the environment, in the other hand, an endothermic reaction is a chemical reaction that absorbs heat from its environment.

In the problem says that an exothermic reaction is performed at a temperature of 35 degrees Celsius.

Now, keeping in mind that a exothermic reaction release heat, we can affirm that the temperature of the sistem will by increased after the reaction occurs.

Finally, the only possible answer is A, because is the only temperature which is superior to the initial temperature (35 degrees Celsius)

dimaraw [331]3 years ago

3 0

Answer:

i think 35 degrees Celsius

Explanation:

cause its the same temperature

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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

4 0

3 years ago

Calculate the volume of compound Y needed to make a 350 pg/ml treatment solution in 2 ml of 1x PBS using a stock solution contai

harina [27]

Answer:

14 mL

Explanation:

To prepare a solution by a concentrated solution, we must use the equation:

C1xV1 = C2xV2, where C is the concentration, V is the volume, 1 is the initial solution and 2 the final solution.

The final solution must have 2 mL and a concentration of 350 pg/mL, and the initial solution has a concentration of 50 pg/mL.

Then:

50xV1 = 350x2

50xV1 = 700

V1 = 700/50

V1 = 14 mL

4 0

3 years ago

I made a cup of coffee on the stove and when I went to check on it four hours later, there was no more water in the kettle.

11Alexandr11 [23.1K]

No the water evaporated
i think :) :)

3 0

3 years ago

Read 2 more answers

Which compound is a polar molecule and has a linear geometry

kirill115 [55]

Answer:

Linear molecule is a molecule in which atoms are deployed in a straight line (under 180° angle). Molecules with an linear electron pair geometries have sp hybridization at the central atom. An example of linear electron pair and molecular geometry are carbon dioxide (O=C=O) and beryllium hydride BeH2.

Explanation:

6 0

3 years ago

10. How many g of Cu(OH)2 can be made from 9.1 x 1025 atoms of O?

il63 [147K]

Molar mass Cu(OH)₂ = 97.561 g/mol

97.561 g Cu(OH)₂ --------------- 6.02x10²³ atoms
? g Cu(OH)₂ -------------------- 9.1x10²⁵ atoms

mass = 9.1x10²⁵ * 97.561 / 6.02x10²³

mass = 8.87x10²⁷ / 6.02x10²³

mass = 14734.2 g

hope this helps!

8 0

3 years ago