I will give Brain list and lot of points

2. HOW MUCH HEAT IS REQUIRED TO BE RELEASED WHEN

jarptica [38.1K]

Answer: -112200J

Explanation:

The amount of heat (Q) released from an heated substance depends on its Mass (M), specific heat capacity (C) and change in temperature (Φ)

Thus, Q = MCΦ

Since,

Q = ?

Mass of water vapour = 30.0g

C = 187 J/ G°C

Φ = (Final temperature - Initial temperature)

= 100°C - 120°C = -20°C

Then apply the formula, Q = MCΦ

Q = 30.0g x 187 J/ G°C x -20°C

Q = -112200J (The negative sign does indicates that heat was released to the surroundings)

Thus, -112200 joules of heat is released when cooling the superheated vapour.

5 0

4 years ago

A volume of 500.0 mL of 0.160 M NaOH is added to 585 mL of 0.200 M weak acid ( K a = 1.28 × 10 − 5 ) . What is the pH of the res

Hitman42 [59]

Answer : The pH of the resulting buffer is, 5.22

Explanation : Given,

$K_a=1.28\times 10^{-5}$

First we have to calculate the moles of $NaOH\text{ and }HA$

$\text{Moles of }NaOH=\text{Concentration of }NaOH\times \text{Volume of solution}}=0.160M\times 0.500L=0.08mol$

and,

$\text{Moles of }HA=\text{Concentration of }HA\times \text{Volume of solution}}=0.200M\times 0.585L=0.117mol$

The balanced chemical reaction is:

$HA+(aq)+OH^-(aq)\rightarrow H_2O(l)+A^-(aq)$

Moles of HA left = 0.117 mol - 0.08 mol = 0.037 mol

Moles of $A^-$ = 0.08 mol

The expression used for the calculation of $pK_a$ is,

$pK_a=-\log (K_a)$

Now put the value of $K_a$ in this expression, we get:

$pK_a=-\log (1.28\times 10^{-5})$

$pK_a=5-\log (1.28)$

$pK_a=4.89$

Now we have to calculate the pH of buffer.

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

$pH=pK_a+\log \frac{[A^-]}{[HA]}$

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

$pH=4.89+\log (\frac{0.08}{0.037})$

$pH=5.22$

Thus, the pH of the resulting buffer is, 5.22

5 0

3 years ago

Orbitals which are equal in energy are referred to as ________.

mash [69]

Degenerate Orbitals

~ Meaning ~

Electron orbitals that have the same energy levels are called degenerate orbitals. When assigning electrons to orbitals in determining electron configurations, the Aufbau principle states that lower energy orbitals are filled before higher energy orbitals.

8 0

3 years ago

In which of the following reactions will Kc = Kp? a. 4 NH3(g) + 3 O2(g) ⇌ 2 N2(g) + 6 H2O(g) b. SO3(g) + NO(g) ⇌ SO2(g) + NO2(g)

Ratling [72]

Answer:

The correct option is <em>b) SO₃(g) + NO(g) ⇌ SO₂(g) + NO₂(g)</em>

Explanation:

The relation between Kc and Kp is given by the following equation:

$Kp = Kc (RT)^{dn}$

where R is the gas constant (0,082 L.atm/K.mol), T is the temperature (in K) and dn is the change in moles.

The change in moles (dn) is calculated as:

dn = moles of products - moles reactants

If dn=0, RT= 1 ⇒ Kc=Kp

We calculate dn for each reaction from the estequiometrial coefficients of products and reactants as follows:

a) 4 NH₃(g) + 3 O₂(g) ⇌ 2 N₂(g) + 6 H₂O(g)

dn= (2+6) - (4+3) = 1 ⇒ Kc ≠ Kp

b) SO₃(g) + NO(g) ⇌ SO₂(g) + NO₂(g)

dn = (1+1) - (1+1)= 0 ⇒ Kc = Kp

c) 2 N₂(g) + O₂(g) ⇌ 2 N₂O(g)

dn= 2 - (2+1) = -1 ⇒ Kc ≠ Kp

d) 2 SO₂(g) + O₂(g) ⇌ 2 SO₃(g)

dn = 2 - (2+1) = -1 ⇒ Kc ≠ Kp

The reaction in which Kc=Kp is b), because reactants and products have the same number of moles.

3 0

3 years ago

When vinegar is added to some marble chips ( calcium carbonate) bubbles of gas are observed, what gas is produced and how can it

Scrat [10]

Answer:

By passing the gas through lime water

Explanation:

The equation of the reaction of vinegar with calcium carbonate in the form of marble chips is shown below;

CaCO3(s) + 2CH3COOH(aq) ---------> Ca(CH3COO)2(aq) + H2O(l) + CO2(g).

We can see from the reaction equation that the gas produced is carbon dioxide. This gas is identified by passing the gas through lime water. If lime water turns milky, then the gas is truly carbon dioxide.

7 0

3 years ago

I will give Brain list and lot of points ​

I will give Brain list and lot of points