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Maru [420]
3 years ago
10

Lactose, C12H22O11, is a naturally occurring sugar found in mammalian milk. A 0.335 M solution of lactose in water has a density

of 1.0432 g/mL at 20 o C. What is the concentration of this solution in the following units?
i) mole fraction
ii) molality
iii) mass percent
Chemistry
1 answer:
Dmitry_Shevchenko [17]3 years ago
5 0

The molality of the solution is 0.00037 m.

<h3>What is concentration?</h3>

The term concentration refers to the amount of solute in a solution.

We have the following information;

Molarity = 0.335 M

Density =  1.0432 g/mL

Temperature = 20 o C

The molality of the solution is obtained from;

m = 0.335 M ×  1.0432 g/mL/ 1000(1.0432 g/mL) - 0.335 M (342 g/mol)

m = 0.344/1043.2 - 114.57

m =  0.344/928.63

m = 0.00037 m

Learn more about molality of solution: brainly.com/question/4580605

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Identify the group number of following oxides/hydrides in Mendeleev
Ivan

Answer:

See explanation

Explanation:

The oxides or hydrides are formed by exchange of valency between the two atoms involved. The group of the atom bonded to oxygen or hydrogen in the binary compound can be deduced by considering the subscript attached to the oxygen or hydrogen atom.

Now let us take the journey;

R2O3- refers to an oxide of a group 13 element, eg Al2O3

R2O - refers to an oxide of group a group 1 element e.gNa2O

RO2 - refers to an oxide of a group 14, 15 or 16 element such as CO2, NO2 or SO2

RH2 - refers to the hydride of a group 12 element Eg CaH2

R2O7 - refers to an oxide of a group 17 element E.g Cl2O7

RH3- refers to a hydride of a group 13 element E.g AlH3

5 0
3 years ago
A 1.0 M solution of a compound with 2 ionizable groups (pKa's = 6.2 and 9.5; 100 mL total) has a pH of 6.8. If a biochemist adds
juin [17]

Answer:

pH = 9,32

Explanation:

The compound with 2 ionizable groups has the following equilibriums:

H₂M ⇄ HM⁻ + H⁺ pka = 6,2

HM⁻ ⇄ M²⁻ + H⁺ pka = 9,5

The reaction of M²⁻ with HCl is:

M²⁻ + HCl → HM⁻ + Cl⁻

The moles of M²⁻ are:

0,100L×1,0M = 0,1moles

And moles of HCl are:

0,060L×1,0M = 0,06moles

That means that moles of M²⁻ will be 0,1-0,06 = 0,04mol and moles of HM⁻ will be the same than HCl, 0,06mol

Using Henderson-Hasselbalch formula:

pH = pka + log₁₀ [M²⁻] / [HM⁻]

Replacing:

pH = 9,5 + log₁₀ [0,04] / [0,06]

<em>pH = 9,32</em>

<em></em>

I hope it helps!

4 0
3 years ago
Can you give me the answers to questions 28 and 29 please?
umka2103 [35]

28. unbalanced because in reactant side the Aluminium is 1 and oxygen is 2 but in the product side the Aluminium is 2 and oxygen is 3 it is not equal so it is unbalanced equation

29. unbalanced because the oxygen atom are not equal in the reactant and the product side

Follow me pls!!

8 0
3 years ago
7) For the reaction 9A (g) + B (g)  5C(g) + 1/6 D (g), it takes 4 and a half minutes for the concentration of C to increase to
viva [34]

Answer: The correct option is, (C) 0.53

Explanation:

The given chemical reaction is:

9A(g)+B(g)\rightarrow 5C(g)+\frac{1}{6}D(g)

The rate of the reaction for disappearance of A and formation of C is given as:

\text{Rate of disappearance of }A=-\frac{1}{9}\times \frac{\Delta [A]}{\Delta t}

Or,

\text{Rate of formation of }C=+\frac{1}{5}\times \frac{\Delta [C]}{\Delta t}

where,

\Delta C = change in concentration of C = 1.33 M

\Delta t = change in time = 4.5 min

Putting values in above equation, we get:

\frac{1}{9}\times \frac{\Delta [A]}{\Delta t}=\frac{1}{5}\times \frac{\Delta [C]}{\Delta t}

\frac{\Delta [A]}{\Delta t}=\frac{9}{5}\times \frac{\Delta [C]}{\Delta t}

\frac{\Delta [A]}{\Delta t}=\frac{9}{5}\times \frac{1.33M}{4.5min}

\frac{\Delta [A]}{\Delta t}=0.53M/min

Thus, the decrease in A during this time interval is, 0.53

5 0
3 years ago
Rhodium crystallizes in a face-centered cubic unit cell. The radius of a rhodium atom is 135 pm. Determine the density of rhodiu
Deffense [45]

Answer:

Density of unit cell ( rhodium) = 12.279 g/cm³

Explanation:

Given that:

The radius (r) of a rhodium atom = 135 pm

The atomic mass of rhodium = 102.90 amu

For a face-centered cubic unit cell,

r = \dfrac{a}{2\sqrt{2}}

where;

a = edge length.

Making "a" the subject of the formula:

a = 2 \sqrt{2} \times r

a = 2 \times 1.414 \times 135 \ pm

a = 381.8 pm

to cm, we get:

a = 381.8 × 10⁻¹⁰ cm

However, recall that:

density \ of \ unit \ cell = \dfrac{mass \ of \ unit \ cell}{volume \ of \unit \ cell}

where;

mass of unit cell = mass of atom × numbers of atoms per unit cell

Also;

mass\  of\ atom =\dfrac{ atomic \ mass}{Avogadro  \  number}

mass\  of\ atom =\dfrac{ 102.9}{6.023 \times 10^{23}}

Recall also that number of atoms in a unit cell for a  face-centered cubic = 4

So;

mass \ of \ unit \ cell= \dfrac{102.90}{6.023 \times 10^{23}}\times 4

mass of unit cell = 6.83380375 × 10⁻²² g

Density  \ of  \ unit \  cell = \dfrac{6.83380375 \times 10^{-22}}{(381.8\times 10^{-10})^3}

Density of unit cell ( rhodium) = 12.279 g/cm³

3 0
3 years ago
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