1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
lubasha [3.4K]
3 years ago
7

25g of magnesium chloride (MgCl2) was dissolved in 250 ml distilled water at 25oC. The density of water was 0.9975g/cm3 . Calcul

ate the concentration in molality.
Chemistry
1 answer:
andriy [413]3 years ago
6 0

Answer:

[MgCl₂] = 1.05 m

Explanation:

Molality is a type of concentration that indicates the moles of solute in 1000g of solvent.

m = mol/kg.

Our solute is MgCl₂. We convert mass to moles:

25 g . 1mol / 95.21 g = 0.262 moles.

Our solvent is water → 250 mL of H₂O

We use density to determine the mass: density = m / V

Density . V = m → 0.9975 g/mL . 250 mL = 249.3 g

We convert from g to kg = 249.3 g . 1kg/1000g = 0.2493kg

molality → 0.262 mol /0.2493kg = 1.05

You might be interested in
A reaction occurs via the following sequence of elementary steps. What is the reaction intermediate?
Trava [24]

Answer:

C is the reaction intermediate.

Explanation:

A reaction intermediate is a molecular structure that is formed during the reaction but then is converted in the final products.

Usually, these reaction intermediates are unestable and, for that reason, the lifetime of these structures is low.

In the reaction, you can see in the first step C is produced, but also, in the second step reacts producing D. As is produced and, immediately consumed,

<h3>C is the reaction intermediate.</h3>
3 0
3 years ago
If 27.3% of a sample of silver-112 decays in 1.52 hours, what is the half-life (in hours to 3 decimal places)?
ICE Princess25 [194]

<u>Answer:</u> The half life of the sample of silver-112 is 3.303 hours.

<u>Explanation:</u>

All radioactive decay processes undergoes first order reaction.

To calculate the rate constant for first order reaction, we use the integrated rate law equation for first order, which is:

k=\frac{2.303}{t}\log \frac{[A_o]}{[A]}

where,

k = rate constant = ?

t = time taken = 1.52 hrs

[A_o] = Initial concentration of reactant = 100 g

[A] = Concentration of reactant left after time 't' = [100 - 27.3] = 72.7 g

Putting values in above equation, we get:

k=\frac{2.303}{1.52hrs}\log \frac{100}{72.7}\\\\k= 0.2098hr^{-1}

To calculate the half life period of first order reaction, we use the equation:

t_{1/2}=\frac{0.693}{k}

where,

t_{1/2} = half life period of first order reaction = ?

k = rate constant = 0.2098hr^{-1}

Putting values in above equation, we get:

t_{1/2}=\frac{0.693}{0.2098hr^{-1}}\\\\t_{1/2}=3.303hrs

Hence, the half life of the sample of silver-112 is 3.303 hours.

6 0
3 years ago
Using the equations and enthalpy values provided, which mathematical expression can be used to determine the unknown enthalpy ch
vlabodo [156]
In order to solve this, we need to make use of Hess' Law.

We are already given the equations and their corresponding deltaH. Using Hess' Law, we can generate this equation:
104 kJ = x - (-1182 kJ) - (-1144 kJ)

Among the choices, the answer is
<span>B.104 = x - [(-1182) + (-1144)] 
</span>
3 0
3 years ago
Read 2 more answers
PLS PLS HELP!!<br> ILL MARK U BRAINLIEST IF U GET IT RIGHT.<br> THIS IS SCIENCE
elixir [45]

Answer:

rocks and magma

Explanation:

there you go lol ok

5 0
3 years ago
Read 2 more answers
The energy of the universe is constant. That what mentioned by the first law of thermodynamics,
Goryan [66]

Answer:

No, ΔE does not always equal zero because it refers to the systems internal energy, which is affected by heat and work

Explanation:

According to the first law of thermodynamics, energy is neither created nor destroyed. This implies that the total energy of a system is always a constant.

So, according to the first law of thermodynamics we have that ΔE = q + w. This means that the value of  ΔE depends on q (heat) and  w(work). Hence ΔE is not always zero since it depends on the respective values of q and w.

5 0
3 years ago
Other questions:
  • Copper(l) sulfide can react with oxygen to produce copper metal by the reaction cu2s + o2 =&gt; 2cu + so2. if 5.00 g of cu2s is
    11·2 answers
  • The change in which ice absorbs energy and melts is a(n)
    7·1 answer
  • As the block slides down the ramp, what type of energy conversion is occurring?
    15·1 answer
  • A sample of pure NO2 is heated to 338 ∘C at which temperature it partially dissociates according to the equation 2NO2(g)⇌2NO(g)+
    12·1 answer
  • The spongy layer of a leaf<br> HELLPROPRPTPR
    15·1 answer
  • If a 0.710 m 0.710 m aqueous solution freezes at − 2.00 ∘ C, −2.00 ∘C, what is the van't Hoff factor, i , i, of the solute?
    14·1 answer
  • How much volume (in cm3) is gained by a person who gains 12.3 lb of pure fat?
    11·1 answer
  • Given, 2Ca + O2 -&gt; 2CaO, what is the 2 located in front of calcium called??
    7·1 answer
  • 5. Which coefficients correctly balance the formula equation
    9·1 answer
  • Calculate the kilojoules needed to heat 231 g of gold from 18 ∘C to 195 ∘C.
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!