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3 years ago

Calculate the moles of solute dissolved in 4.2 dm3 of a 0.5 mol / dm3 solution.

Chemistry

1 answer:

Archy [21]3 years ago

8 0

Answer:

Example

0.5 mol of sodium hydroxide is dissolved in 2 dm3 of water. Calculate the concentration of the sodium hydroxide solution formed.

Concentration =

Concentration = 0.25 mol/dm3

Volume units

Volumes used in concentration calculations must be in dm3, not in cm3. It is useful to know that 1 dm3 = 1000 cm3. This means:

divide by 1000 to convert from cm3 to dm3

multiply by 1000 to convert from dm3 to cm3

For example, 250 cm3 is 0.25 dm3 (250 ÷ 1000). It is often easiest to convert from cm3 to dm3 before continuing with a concentration calculation.

Question

100 cm3 of dilute hydrochloric acid contains 0.02 mol of dissolved hydrogen chloride. Calculate the concentration of the acid in mol/dm3.

Reveal answer

Converting between units

The relative formula mass of the solute is used to convert between mol/dm3 and g/dm3:

to convert from mol/dm3 to g/dm3, multiply by the relative formula mass

to convert from g/dm3 to mol/dm3, divide by the relative formula mass

Remember: the molar mass is the Ar or Mr in grams per mol.

Example

Calculate the concentration of 0.1 mol/dm3 sodium hydroxide solution in g/dm3. (Mr of NaOH = 40)

Concentration = 0.1 × 40

= 4 g/dm3

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Draw the most reasonable lewis structure of a molecule that contains a n atom, a c atom, and a h atom. include any formal charge

faust18 [17]

H:C:::N: (hydrogen cyanide). All atoms have formal charge of 0.

4 0

3 years ago

Two separate masses of zinc were measured on a laboratory balance. The first zinc had a sample mass of 210.10g, and the second z

wlad13 [49]

Answer:

Density is 7.15 g /mL.

Mass is 445.2 g.

Explanation:

Density:

Density is equal to the mass of substance divided by its volume.

Units:

SI unit of density is Kg/m3.

Other units are given below,

g/cm3, g/mL , kg/L

Formula:

D=m/v

D= density

m=mass

V=volume

Symbol:

The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.

Given data:

Mass of first zinc sample = 210.10 g

Mass of second zinc sample = 235.10 g

Combined volume = 62.3 mL

Density of combined sample ?

Mass of combined sample = ?

Solution:

Mass of combined sample = 210.10 g + 235.10 g = 445.2 g

density = mass / volume

density = 445.2 g / 62.3 mL

density = 7.15 g /mL

3 0

3 years ago

if a saline bag has a molarity of 0.155 and 0.75 L are given to a patient how many grams of NaCl did the patient receive?

katrin [286]

Answer:

Mass = 6.79 g

Explanation:

Molarity = 0.155

Volume = 0.75L

Mass = ?

The relationship between these quantities is given as;

Molarity = Number of moles / Volume

Number of moles = Volume * Molarity

Number of moles = 0.75 * 0.155 = 0.11625 moles

Number of moles = Mass / Molar mass

Mass = Molar mass * Number of moles

Mass = 58.44277 g/mol * 0.11625 mol

Mass = 6.79 g

8 0

3 years ago

Write the charge and full ground-state electron configuration of the monatomic ion most likely to be formed by each:

Sladkaya [172]

Answer:

Part A:

Charge is $P^{3-}$

Configuration is $1s^2 2s^22p^63s^23p^6$

Part B:

Charge is $Mg^{2+}$

Configuration is $1s^2 2s^22p^6$

Part C:

Charge is $Se^{2-}$

Configuration is $1s^2 2s^22p^63s^23p^64s^23d^{10}4p^6$

Explanation:

Monatomic ions:

These ions consist of only one atom. If they have more than one atom then they are poly atomic ions.

Examples of Mono Atomic ions: $Na^+, Cl^-, Ca^2^+$

Part A:

For P:

Phosphorous (P) has 15 electrons so it require 3 more electrons to stabilize itself.

Charge is $P^{3-}$

Full ground-state electron configuration of the mono atomic ion:

$1s^2 2s^22p^63s^23p^6$

Part B:

For Mg:

Magnesium (Mg) has 12 electrons so it requires 2 electrons to lose to achieve stable configuration.

Charge is $Mg^{2+}$

Full ground-state electron configuration of the mono atomic ion:

$1s^2 2s^22p^6$

Part C:

For Se:

Selenium (Se) has 34 electrons and requires two electrons to be stable.

Charge is $Se^{2-}$

Full ground-state electron configuration of the mono atomic ion:

$1s^2 2s^22p^63s^23p^64s^23d^{10}4p^6$

8 0

3 years ago

If the density of pure water is 0.9922 g/mL at 40 ºC, calculate its theoretical molarity at that temperature. Report to 4 sig fi

OleMash [197]

Answer is: theoretical molarity of water is 55.1222 mol/L.<span>
d(H</span>₂O) = 0.9922 g/mL.
M(H₂O) = 2 · Ar(H) + Ar(O) · g/mol.
M(H₂O) = 2 + 16 · g/mol = 18 g/mol.
c(H₂O) = d(H₂O) ÷ M(H₂O).
c(H₂O) = 0.9922 g/mL ÷ 18 g/mol.
c(H₂O) = 0.0551 mol/mL.
c(H₂O) = 0.0551 mol/mL · 1000 mL/L = 55.1222 mol/L.

3 0

4 years ago