Find the measure of the numbered angle. m∠2=

Which of the following best describes the rate of motion of a glacier?

Minchanka [31]

Same speed as Continental drift

8 0

3 years ago

You place 36.5 ml of 0.266 M Ba(OH)2 in a coffee-cup calorimeter at 25.00°C and add 56.6 ml of 0.648 M HCl, also at 25.00°C. Aft

olya-2409 [2.1K]

Answer : The enthalpy of reaction $(\Delta H_{rxn})$ is, -96.9 kJ/mole

Explanation :

First we have to calculate the mass of solution.

$Mass=Density\times Volume$

Volume of solution = Volume of HCl + Volume of $Ba(OH)_2$

Volume of solution = 56.6 mL + 36.5 mL

Volume of solution = 93.1 mL

Density of solution = 1 g/mL

$Mass=1g/mL\times 93.1mL=93.1g$

The mass of solution is, 93.1 grams.

Now we have to calculate the heat released in the system.

Formula used :

$Q=m\times c\times \Delta T$

or,

$Q=m\times c\times (T_2-T_1)$

where,

Q = heat released = ?

m = mass = 93.1 g

$C_p$ = specific heat capacity of water = $4.184J/g^oC$

$T_1$ = initial temperature = $25.0^oC$

$T_2$ = final temperature = $29.83^oC$

Now put all the given value in the above formula, we get:

$Q=93.1g\times 4.184J/g^oC\times (29.83-25.00)^ioC$

$Q=1881.43J=1.88kJ$ (1 kJ = 1000 J)

Now we have to calculate the moles of $Ba(OH)_2$ and HCl.

$\text{Moles of }Ba(OH)_2=\text{Concentration of }Ba(OH)_2\times \text{Volume of solution}$

$\text{Moles of }Ba(OH)_2=0.266M\times 0.0365L=9.71\times 10^{-3}mol$

and,

$\text{Moles of }HCl=\text{Concentration of }HCl\times \text{Volume of solution}$

$\text{Moles of }HCl=0.648M\times 0.0566L=3.66\times 10^{-2}mol$

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

$Ba(OH)_2+2HCl\rightarrow BaCl_2+2H_2O$

From the balanced reaction we conclude that

As, 1 mole of $Ba(OH)_2$ react with 2 mole of $HCl$

So, $9.71\times 10^{-3}$ moles of $Ba(OH)_2$ react with $9.71\times 10^{-3}\times 2=0.0194$ moles of $HCl$

From this we conclude that, $HCl$ is an excess reagent because the given moles are greater than the required moles and $Ba(OH)_2$ is a limiting reagent and it limits the formation of product.

Now we have to calculate the moles of $H_2O$

From the reaction, we conclude that

As, 1 mole of $Ba(OH)_2$ react to give 2 mole of $H_2O$

So, $9.71\times 10^{-3}$ moles of $Ba(OH)_2$ react with $9.71\times 10^{-3}\times 2=0.0194$ moles of $H_2O$

Now we have to calculate the change in enthalpy of the reaction.

$\Delta H_{rxn}=-\frac{q}{n}$

where,

$\Delta H_{rxn}$ = enthalpy of reaction = ?

q = heat of reaction = 1.88 kJ

n = moles of reaction = 0.0194 mole

Now put all the given values in above expression, we get:

$\Delta H_{rxn}=-\frac{1.88kJ}{0.0194mole}=-96.9kJ/mole$

The negative sign indicates that the heat is released.

Therefore, the enthalpy of reaction $(\Delta H_{rxn})$ is, -96.9 kJ/mole

3 0

4 years ago

Fix the formula for KF2<br> Write out the full correct formula?

Korvikt [17]

Given :

A chemical compound $KF_2$ .

To Find :

Fix the formula for $KF_2$ and write the full correct formula.

Solution :

We know, Potassium( K ) and Fluorine( F ) both have a valency of 1 i.e potassium can donate one electron and Fluorine can accept one electron only.

So, the chemical formula $KF_2$ is wrong because no element has filled electron.

Therefore, to stabilise the molecule, 1 Potassium atom should make a bond from 1 Fluorine i.e KF ( correct formula ) .

Hence, this is the required solution.

7 0

3 years ago

What is a solution of zinc and copper?<br>five letter word

Lana71 [14]

Answer:

Brass

Explanation:

Brass is an alloy of copper and zinc, in proportions which can be varied to achieve varying mechanical and electrical properties.

5 0

3 years ago

Mendeleev created this table as he noticed that a

Nimfa-mama [501]

Answer:

Mendeleev had left the noble gases out of his periodic table.

Explanation:

Mendeleev's periodic table is pictured in the image attached to the question.

Mendeleev's table obviously lacked the noble gases. The reason for this grave omission is simple; the noble gases were not known as at the time when he formulated his periodic table. There weren't any known elements whose properties were similar to the properties of the noble gases. This would have lead him to suspect their existence.

4 0

3 years ago

Find the measure of the numbered angle. m∠2= _