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lana66690 [7]
3 years ago
15

In h-atom if x is radius of first bohrs orbit de broglie wavelength of an atom in 3rd orbit is a.3πx b.6πx c.9x/2 d.x/2

Chemistry
1 answer:
Step2247 [10]3 years ago
5 0

Answer:

can you type question properly.

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A solution of NaCl ( aq ) is added slowly to a solution of lead nitrate, Pb ( NO 3 ) 2 ( aq ) , until no further precipitation o
statuscvo [17]

Answer : The molarity of Pb(NO_3)_2  solution is, 0.352 M

Explanation :

First we have to calculate the moles of PbCl_2

\text{Moles of }PbCl_2=\frac{\text{Given mass }PbCl_2}{\text{Molar mass }PbCl_2}

Molar mass of PbCl_2 = 278.1 g/mol

\text{Moles of }PbCl_2=\frac{19.58g}{278.1g/mol}=0.07041mol

Now we have to calculate the moles of CaCl_2

The balanced chemical equation is:

Pb(NO_3)_2(aq)+2NaCl(aq)\rightarrow PbCl_2(s)+2NaNO_3(aq)

From the balanced reaction we conclude that

As, 1 mole of PbCl_2 produced from 1 mole of Pb(NO_3)_2

So, 0.07041 mole of PbCl_2 produced from 0.07041 mole of Pb(NO_3)_2

Now we have to calculate the molarity of Pb(NO_3)_2

\text{Molarity of }Pb(NO_3)_2=\frac{\text{Moles of }Pb(NO_3)_2}{\text{Volume of solution in (L)}}

\text{Molarity of }Pb(NO_3)_2=\frac{0.07041mol}{0.200L}=0.352M

Therefore, the molarity of Pb(NO_3)_2  solution is, 0.352 M

4 0
3 years ago
An element's atomic number is 60. How many protons would an atom of this element have? __protons
Lady_Fox [76]
If an an element has an atomic number of 60, then there would me 60 protons.
Something that helps me is APE.
The atomic number is the same as the number of protons and electrons.
3 0
3 years ago
How much heat energy is required to convert 48.3 g of solid ethanol at -114.5 degree C to gasesous ethanol at 135.3 degree C? Th
OLEGan [10]

Answer:

7.21 × 10⁴ J

Explanation:

Ethanol is solid below -114.5°c, liquid between -114.5°C and 78.4°C, and gaseous above 78.4°C.

<em>How much heat energy is required to convert 48.3 g of solid ethanol at -114.5°C to gaseous ethanol at 135.3 °C?</em>

<em />

We need to calculate the heat required in different stages and then add them.

The moles of ethanol are:

48.3g.\frac{1mol}{46.07g} =1.05mol

Solid-liquid transition

Q₁ = ΔHfus . n = (4.60 kJ/mol) . 1.05 mol = 4.83 kJ = 4.83 × 10³ J

where,

ΔHfus: molar heat of fusion

n: moles

Liquid: from -114.5°C to 78.4°C

Q₂ = c(l) . m . ΔT = (2.45 J/g.°C) . 48.3g . [78.4°C-(-114.5°C)] = 2.28 × 10⁴ J

where,

c(l): specific heat capacity of the liquid

ΔT: change in the temperature

Liquid-gas transition

Q₃ = ΔHvap . n = (38.56 kJ/mol) . 1.05 mol = 40.5 kJ = 40.5 × 10³ J

where,

ΔHvap: molar heat of vaporization

Gas: from 78.4°C to 135.3°C

Q₄ = c(g) . m . ΔT = (1.43 J/g.°C) . 48.3g . (135.3°C-78.4°C) = 3.93 × 10³ J

where

c(g): specific heat capacity of the gas

Total heat required

Q₁ + Q₂ + Q₃ + Q₄ = 4.83 × 10³ J + 2.28 × 10⁴ J + 40.5 × 10³ J + 3.93 × 10³ J = 7.21 × 10⁴ J

3 0
3 years ago
Convert the pressure 525.4 torr to kPa.
Oduvanchick [21]

Answer:

Option A. 70.0 KPa.

Explanation:

Data obtained from the question include:

Pressure (torr) = 525.4 torr

Pressure (kPa) =?

The pressure expressed in torr can be converted kPa as shown below:

760 torr = 101.325 KPa

Therefore,

525.4 torr = (525.4 x 101.325) / 760 = 70.0 KPa.

Therefore, 525.4 torr is equivalent to 70.0 KPa.

3 0
3 years ago
Read 2 more answers
Using the equations 2 Sr(s) + O₂ (g) → 2 SrO (s) ∆H° = -1184 kJ/mol SrO (s) + CO₂ (g) → SrCO₃ (s) ∆H° = -234 kJ/mol CO₂ (g) → C(
kkurt [141]

<u>Answer:</u> The \Delta H^o_{rxn} for the reaction is 72 kJ.

<u>Explanation:</u>

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction follows:

2SrCO_3(s)\rightarrow 2Sr(s)+2C(s)+3O_2(g)      \Delta H^o_{rxn}=?

The intermediate balanced chemical reaction are:

(1) 2Sr(s)+O_2(g)\rightarrow 2SrO(s)    \Delta H_1=-1184kJ

(2) SrO(s)+CO_2(g)\rightarrow SrCO_3(s)     \Delta H_2=-234kJ      ( × 2)

(3) CO_2(g)\rightarrow C(s)+O_2(g)     \Delta H_3=394kJ    ( × 2)

The expression for enthalpy of the reaction follows:

\Delta H^o_{rxn}=[1\times (\Delta H_1)]+[2\times (-\Delta H_2)]+[2\times (\Delta H_3)]

Putting values in above equation, we get:

\Delta H^o_{rxn}=[(1\times (-1184))+(2\times -(-234))+(2\times (394))]=72kJ

Hence, the \Delta H^o_{rxn} for the reaction is 72 kJ.

4 0
3 years ago
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