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Svetach [21]
3 years ago
5

How many moles of sodium chloride (NaCl) solute are in 315 grams of a 91.0 percent by mass solution?

Chemistry
1 answer:
Anni [7]3 years ago
8 0
Hope this helps you.

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Energy can be .................. From one form to another................. Can be burned to make heat or electricity.
nataly862011 [7]

Answer:

transferred

Energy

Explanation:

Energy is the ability to change the state of bringing about a work leading to movement or generating electromagnetic radiation. There are actually many forms of energy. So, kinetic energy is a form of energy related to the movement of a body. The combustion, in turn, retrieves the potential energy chemical contained in fuels. Solar panels capture light energy to transform it into electrical energy.

3 0
3 years ago
Why does an exothermic reaction need activation energy?
andrey2020 [161]

Answer:

Activation energy is needed so reactants can move together, overcome forces of repulsion, and to begin breaking bonds.

Explanation:

6 0
3 years ago
The Ka for formic acid (HCO2H) is 1.8 × 10-4. What is the pH of a 0.35 M aqueous solution of sodium formate (NaHCO2)?
anzhelika [568]

Answer:

9.36

Explanation:

Sodium formate is the conjugate base of formic acid.

Also,

K_a\times K_b=K_w

K_b for sodium formate is K_b=\frac {K_w}{K_a}

Given that:

K_a of formic acid = 1.8\times 10^{-4}

And, K_w=10^{-14}

So,

K_b=\frac {10^{-14}}{1.8\times 10^{-4}}

K_b=5.5556\times 10^{-11}

Concentration = 0.35 M

HCOONa    ⇒     Na⁺ +    HCOO⁻

Consider the ICE take for the formate  ion as:

                                   HCOO⁻ + H₂O   ⇄   HCOOH + OH⁻

At t=0                              0.35                            -              -

At t =equilibrium           (0.35-x)                          x           x            

The expression for dissociation constant of sodium formate is:

K_{b}=\frac {[OH^-][HCOOH]}{[HCOO^-]}

5.5556\times 10^{-11}=\frac {x^2}{0.35-x}

Solving for x, we get:

x = 0.44×10⁻⁵  M

pOH = -log[OH⁻] = -log(0.44×10⁻⁵) = 4.64

pH + pOH = 14

So,

<u>pH = 14 - 4.64 = 9.36</u>

5 0
3 years ago
Which two elements make up the greatest percentages by mass in Earth’s crust?
yuradex [85]
<h2><u>Answer</u> :</h2>

The most appropriate option is :

\hookrightarrow \bf2. \:  \mathrm{ \underline{oxygen \:  \: and \:  \: silicon}}

Since, they are the most abundant elements found in Earth's Crust.

  • Oxygen (46%)

  • Silicon (28%)

\circ  { \underline{ \boxed{ \sf{ \color{green}{ \mathrm{hope \:  \: it \:  \: helps \:  \: you .....}}}}}}∘

4 0
2 years ago
Write Qc for each of the following:(1) Gaseous sulfur tetrafluoride reacts with liquid water to produce gaseous sulfur dioxide a
snow_tiger [21]

Answer : The expression for reaction quotient will be :

(1) Q_c=\frac{[SO_2][HF]^4}{[SF_4]}

(2) Q_c=\frac{[O_2]^2[Xe]}{[XeF_2]}

Explanation :

Reaction quotient (Q_c) : It is defined as the measurement of the relative amounts of products and reactants present during a reaction at a particular time.

(1) The given balanced chemical reaction is,

SF_4(g)+2H_2O(l)\rightarrow SO_2(g)+4HF(g)

In this expression, only gaseous or aqueous states are includes and pure liquid or solid states are omitted.  So, the expression for reaction quotient will be :

Q_c=\frac{[SO_2][HF]^4}{[SF_4]}

(2) The given balanced chemical reaction is,

2MoO_2(s)+XeF_2(g)\rightarrow 2MoF(l)+Xe(g)+2O_2(g)[/texIn this expression, only gaseous or aqueous states are includes and pure liquid or solid states are omitted.  So, the expression for reaction quotient will be :[tex]Q_c=\frac{[O_2]^2[Xe]}{[XeF_2]}

7 0
3 years ago
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