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3 years ago

12

Which change will decrease the number of effective collisions during a chemical reaction? A. adding a catalyst B. increasing the

surface area C. decreasing the temperature D. increasing the reactant concentrations E. increasing the volume of the reactants

2 answers:

Juliette [100K]3 years ago

6 0

Correct Answer: Is C, decreasing the temperature.

<u>You are welcome, friend.</u>

Ipatiy [6.2K]3 years ago

5 0

The answer to your question is C

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A compound is 42.9% C, 2.4% H, 16.7% N, and 38.1% O, by mass. Addition of 6.45 g of this compound to 50.0 mL benzene, lowers the

Romashka [77]

This is an incomplete question, here is a complete question.

A compound is 42.9% C, 2.4% H, 16.7% N and 38.1% O by mass. Addition of 6.45 g of this compound to 50.0 mL benzene, C₆H₆ (d= 0.879 g/mL; Kf= 5.12 degrees Celsius/m), lowers the freezing point from 5.53 to 1.37 degrees Celsius. What is the molecular formula of this compound?

Answer : The molecular of the compound is, $C_6H_4N_2O_4$

Explanation :

First we have to calculate the mass of benzene.

$\text{Mass of benzene}=\text{Density of benzene}\times \text{Volume of benzene}$

$\text{Mass of benzene}=0.879g/mL\times 50.0mL=43.95g$

Now we have to calculate the molar mass of unknown compound.

Given:

Mass of unknown compound (solute) = 6.45 g

Mass of benzene (solvent) = 43.95 g = 0.04395 kg

Formula used :

$\Delta T_f=K_f\times m\\\\\Delta T_f=K_f\times\frac{\text{Mass of unknown compound}}{\text{Molar mass of unknown compound}\times \text{Mass of benzene in Kg}}$

where,

$\Delta T_f$ = change in freezing point = $5.53-1.37=4.16^oC$

$\Delta T_s$ = freezing point of solution

$\Delta T^o$ = freezing point of benzene

Molal-freezing-point-depression constant $(K_f)$ for benzene = $5.12^oC/m$

m = molality

Now put all the given values in this formula, we get

$4.16^oC=(5.12^oC/m)\times \frac{6.45g}{\text{Molar mass of unknown compound}\times 0.04395kg}$

$\text{Molar mass of unknown compound}=180.6g/mol$

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of C = 42.9 g

Mass of H = 2.4 g

Mass of N = 16.7 g

Mass of O = 38.1 g

Molar mass of C = 12 g/mole

Molar mass of H = 1 g/mole

Molar mass of N = 14 g/mole

Molar mass of O = 16 g/mole

Step 1 : convert given masses into moles.

Moles of C = $\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{42.9g}{12g/mole}=3.575moles$

Moles of H = $\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{2.4g}{1g/mole}=2.4moles$

Moles of N = $\frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{16.7g}{14g/mole}=1.193moles$

Moles of O = $\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{38.1g}{16g/mole}=2.381moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = $\frac{3.575}{1.193}=2.99\approx 3$

For H = $\frac{2.4}{1.193}=2.01\approx 2$

For N = $\frac{1.193}{1.193}=1$

For O = $\frac{2.381}{1.193}=1.99\approx 2$

The ratio of C : H : N : O = 3 : 2 : 1 : 2

The mole ratio of the element is represented by subscripts in empirical formula.

The Empirical formula = $C_3H_2N_1O_2$

The empirical formula weight = 3(12) + 2(1) + 1(14) + 2(16) = 84 gram/eq

Now we have to calculate the molecular formula of the compound.

Formula used :

$n=\frac{\text{Molecular formula}}{\text{Empirical formula weight}}$

$n=\frac{180.6}{84}=2$

Molecular formula = $(C_3H_2N_1O_2)_n=(C_3H_2N_1O_2)_2=C_6H_4N_2O_4$

Therefore, the molecular of the compound is, $C_6H_4N_2O_4$

3 0

3 years ago

Whick ions profuce similar colors in the flame tests?

arlik [135]

Ba2+ and Cu2+, and Sr2+ and Li+

5 0

3 years ago

How much time would it take to distribute one avagadro's number of wheat grains if 10^10 grains are A)1.9*10^2 years B)1.9*10^10

Makovka662 [10]

Answer:

It takes 1.9 $\times 10^{6}$ years to distribute all the grains.

Explanation:

In one second, $10^{10}$ grains of wheat are distributed.

We are supposed to find the time it would take to Distribute Avogadro number of grains.

1 avogadro number = 6.022 $\times 10^{23}$

Number of grains distributed in 1 day = 86400 $\times 10^{10}$

= 8.64 $\times 10^{14}$

Number of grains distributed in 1 year= 8.64 $\times 10^{14} \times 365$

= 3.1536 $\times 10^{17}$

Time taken = $\frac{Number of grains to be distributed}{grains distributed in 1 year}$

= $\frac {6.022 \times 10^{23}}{3.1536\times 10^{17}}$

= 1.9 $\times 10^{6}$

7 0

3 years ago

The energy required to break existing chemical bonds in reactants is called the ______ energy.

mixer [17]

The energy required to break existing chemical bonds in reactants is called the activation energy.

<h3>What is activation energy?</h3>

Activation energy in chemistry is the energy required to initiate a chemical reaction.

Chemical reactions involve the breaking of chemical bonds in substances called reactants to form new substances called products.

The energy required to break the bond in the existing reactants thus elevating these substances to a state of high activation is known as activation energy.

Therefore, it can be said that energy required to break existing chemical bonds in reactants is called the activation energy.

Learn more about activation energy at: brainly.com/question/11334504

#SPJ1

8 0

2 years ago

A(n)__________<br>accepts electrons and becomes___________<br>

Oksi-84 [34.3K]

it's the first one. the one with ox in it

8 0

3 years ago