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castortr0y [4]
3 years ago
10

Since helium is lighter than air, it is difficult to measure the mass of a sample, so to find out the mass of helium in a birthd

ay balloon, a student transferred the helium to a fixed 1.50 L vessel at 25.0 °C and found the pressure to be 3.04 atm. What mass of helium is in the balloon?
Chemistry
1 answer:
d1i1m1o1n [39]3 years ago
6 0

Answer:

0.7457 g is the mass of the helium gas.

Explanation:

Given:  

Pressure = 3.04 atm

Temperature = 25.0 °C

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15  

So,  

T₁ = (25.0 + 273.15) K = 298.15 K  

Volume = 1.50 L

Using ideal gas equation as:

PV=nRT

where,  

P is the pressure

V is the volume

n is the number of moles

T is the temperature  

R is Gas constant having value = 0.0821 L.atm/K.mol

Applying the equation as:

3.04 atm × 1.50 L = n × 0.0821 L.atm/K.mol × 298.15 K  

<u>⇒n = 0.1863 moles</u>

Molar mass of helium = 4.0026 g/mol

The formula for the calculation of moles is shown below:

moles = \frac{Mass\ taken}{Molar\ mass}

Thus,

0.1863\ mole= \frac{Mass}{4.0026\ g/mol}

Mass_{He}= 0.7457\ g

<u>0.7457 g is the mass of the helium gas. </u>

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5. Write a net ionic equation that occurs in a Na2HPO4/NaH2PO4 buffer solution when: A) a small amount of HCl is added (2 points
labwork [276]

Answer: (A) H_{3}O^{+}(aq) + HPO^{2-}_{4}(aq) \rightarrow H_{2}PO^{2-}_{4}(aq) + H_{2}O(l)

(B) H_{2}PO^{-}_{4}(aq) + OH^{-}(aq) \rightarrow HPO^{2-}_{4}(aq) + H_{2}O(l)

Explanation:

(A) As we know that HCl is a strong acid and when it is added to an aqueous solution then it leads to increase in the concentration of hydrogen ions. And, when an acid or base is added to a solution then any resistance by the solution in changing the pH of the solution is known as a buffer.

This means that addition of buffer into the given solution will not cause much change in the concentration of H_{3}O^{+} in large amount.

As both the buffer components are salt then they will remain dissociated as follows.

       Na_{2}HPO_{4}(aq) \rightarrow 2Na^{+}(aq) + HPO^{2-}_{4}(aq)

 NaH_{2}PO_{4}(aq) \rightarrow Na^{+}(aq) + H_{2}PO^{-}_{4}(aq)

Hence, net ionic equation will be as follows.

       H_{3}O^{+}(aq) + HPO^{2-}_{4}(aq) \rightarrow H_{2}PO^{2-}_{4}(aq) + H_{2}O(l)

(B)  When we add small amount of sodium hydroxide into the solution then there will occur an increase in concentration of hydroxide ions into the solution. But then due to the presence of buffer there will occur not much change in concentration and the acid will get converted into salt.

     NaOH(aq) \rightarrow Na^{+}(aq) + OH^{-}(aq)

The net ionic equation is as follows.

        H_{2}PO^{-}_{4}(aq) + OH^{-}(aq) \rightarrow HPO^{2-}_{4}(aq) + H_{2}O(l)

7 0
3 years ago
An aluminum can holds 350 mL of gas at 0 C and 1.0 atm. what is the new volume if the can is heated to 10 C and the pressure ins
Mademuasel [1]

Answer:

Final volume of the gas is 4.837mL

Explanation:

Initial volume (V1) = 350mL = 0.35L

Initial temperature (T1) = 0°C = (0 + 273.15)k = 273.15k

Initial pressure (P1) = 1.0atm

Final volume (V2) = ?

Final temperature (T2) = 10°C = (10 + 273.15)k = 283.15K

Final pressure (P2) = 75atm

To solve this question, we'll have to use combined gas equation which is the combination of all gas law I.e Charle's laws, Boyle's law, Pressure law etc.

According to combined gas equation,

(P1 × V1) / T1 = (P2 × V2) / T2

Make V2 the subject of formula,

V2 = (P1 × V1 × T2) / (P2 × T1)

V2 = (1.0 × 0.35 × 283.15) / (75 × 273.15)

V2 = 99.1025 / 20,486.25

V2 = 0.004837L

V2 = 4.837mL

The final volume of the gas is 4.837mL

5 0
3 years ago
Read 2 more answers
I have these orgo problems for homework and I have no idea where to even begin. We have to find missing reagents and products ba
almond37 [142]

Answer:

Honestly makes no sense sorry :(

Explanation:

I can try though.. There are three types of selectivity possible for any synthesis: (i) Chemoselectivity is deciding which group reacts. (ii) Regioselectivity is where the reaction takes place in that group. (iii) Stereoselectivity is how the group reacts with respect to the stereochemistry of the product.

A stereospecific mechanism specifies the stereochemical outcome of a given reactant, whereas a stereoselective reaction selects products from those made available by the same, non-specific mechanism acting on a given reactant. Of stereoisomeric reactants, each behaves in its own specific way.

I tried to explain it the best I could.

Hopefully this helps you :)

Feel free to correct me If it was wrong

5 0
3 years ago
PLEASE HELPPPP IM GIVING THE TEST RN
Tom [10]

Answer:

answer is c

Explanation:

single replacement

6 0
3 years ago
What is the general structure for a chemical equation?
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