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aleksandrvk [35]

3 years ago

8

Which sample contains the greatest number of moles of cl? which sample contains the greatest number of moles of ? 3.8 mol hcl 4.

2 mol naclo3 1.7 mol ch2cl2 2.2 mol mg(clo4)2?

1 answer:

ollegr [7]3 years ago

3 0

The sample with greatest number of moles of Cl is calculated as follows

calculate the number of moles of Cl in each sample by multipying mole with number of chlorine molecule

Hcl= 3.8 moles x 1 = 3.8 moles

NaCIO3 = 4.2 moles x 1 = 4.2 moles

CH2Cl2= 1.7 moles x2 = 3.4 moles

Mg (ClO4)2 =2.2 moles x 2 = 4.4 moles

Mg(Cl)4)2 sample is the one with greatest number of Cl moles

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You determine that it takes 26.0 mL of base to neutralize a sample of your unknown acid solution. The pH of the solution was 7.8

Lubov Fominskaja [6]

Complete Question

You determine that it takes 26.0 mL of base to neutralize a sample of your unknown acid solution. The pH of the solution was 7.82 when exactly 13 mL of base had been added, you notice that the concentration of the unknown acid was 0.1 M. What is the pKa of your unknown acid?

Answer:

The pK_a value is $pK_a =7.82$

Explanation:

From the question we are told

The volume of base is $V_B = 26.mL = 0.0260L$

The pH of solution is $pH = 7.82$

The concentration of the acid is $C_A = 0.1M$

From the pH we can see that the titration is between a strong base and a weak acid

Let assume that the the volume of acid is $V_A = 18mL= 0.018L$

Generally the concentration of base

$C_B = \frac{C_AV_A}{C_B}$

Substituting value

$C_B = \frac{0.1 * 0.01800}{0.0260}$

$C_B= 0.0692M$

When 13mL of the base is added a buffer is formed

The chemical equation of the reaction is

$HA_{(aq)} + OH^-_{(aq)} --------> A^{+}_{(aq)} + H_2 O_{(l)}$

Now before the reaction the number of mole of base is

$No \ of \ moles[N_B] = C_B * V_B$

Substituting value

$N_B = 0.01300 * 0.0692$

$= 0.0009 \ moles$

Now before the reaction the number of mole of acid is

$No \ of \ moles = C_B * V_B$

Substituting value

$N_A = 0.01800 *0.1$

$= 0.001800 \ moles$

Now after the reaction the number of moles of base is zero i.e has been used up

this mathematically represented as

$N_B ' = N_B - N_B = 0$

The number of moles of acid is

$N_A ' = N_A - N_B$

$= 0.0009\ moles$

The pH of this reaction can be mathematically represented as

$pH = pK_a + log \frac{[base]}{[acid]}$

Substituting values

$7.82 = pK_a +log \frac{0.0009}{0.0009}$

$pK_a =7.82$

8 0

2 years ago

Select the item(s) that are organs in either a plant or human

Nataly_w [17]

Plant: leaf tissue
Human: lungs

3 0

3 years ago

Mercury (Hg) poisoning is a debilitating disease that is often fatal. In the human body, mercury reacts with essential enzymes l

alisha [4.7K]

Answer:

6 x 10⁵ kg Hg

Explanation:

The mass of mercury in the entire lake is found by multiplying the concentration of the mercury by the volume of the lake.

The volume of the lake is calculated in cubic feet:

V = (SA)x(depth) = (100mi²)(5280ft/mi)² x (20ft) = 5.57568 x 10¹⁰ ft³

Cubic feet are then converted to mL (1cm³=1mL)

(5.57568 x 10¹⁰ ft³) x (12in/ft)³ x (2.54cm/in)³ = 1.578856752 x 10¹⁵ mL

The mass of mercury is then found:

m = CV = (0.4μg/mL)(1g/10⁶μg)(1kg/1000g) x (1.578856752 x 10¹⁵ mL) = 6 x 10⁵ kg Hg

3 0

3 years ago

Acetic acid has a Kb of 2.93 °C/m and a normal boiling point of 118.1 °C. What would be the boiling point of a solution made by

alexdok [17]

Boiling point elevation is given as:

ΔTb=iKbm

Where,

ΔTb=elevation in the boiling point

that is given by expression:

ΔTb=Tb (solution) - Tb (pure solvent)

Here Tb (pure solvent)=118.1 °C

i for CaCO3= 2

Kb=2.93 °C/m

m=Molality of CaCO₃:

Molality of CaCO₃=Number of moles of CaCO₃/ Mass of solvent (Kg)

=(Given Mass of CaCO3/Molar mass of CaCO₃)/ Mass of solvent (Kg)

=(100.0÷100 g/mol)/0.4

= 2.5 m

So now putting value of m, i and Kb in the boiling point elevation equation we get:

ΔTb=iKbm

=2×2.93×2.5

=14.65 °C

boiling point of a solution can be calculated:

ΔTb=Tb (solution) - Tb (pure solvent)

14.65=Tb (solution)-118.1

Tb (solution)=118.1+14.65

=132.75

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In the quantum mechanical model, what two words do they use to describe<br> particles?

miskamm [114]

Answer:

This question is incomplete

Explanation:

This question is incomplete but one can assume the answer from the definition of quantum mechanics. Quantum mechanics is the science that describes particles in nature at the atomic and subatomic particle (electron, proton and neutron) level. Thus it can be assumed that atoms and subatomic particles are used to broadly describe particles.

5 0

3 years ago