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3 years ago

One of the main goals of environmental science is to help humans use the environment in a way that is economically profitable.

Chemistry

1 answer:

kkurt [141]3 years ago

5 0

Answer:

true this is correct its your econimically

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Which example best describes a reflex action?

Pepsi [2]

I think the answer would be b because your throat is reacting to the cough?

6 0

3 years ago

A sample of gas has a pressure of 3.2 atmospheres at a temperature of 301 Kelvin. What would be the pressure of the same sample

Advocard [28]

P1/T1=P2/T2 Gay Lussac's Law

3.2/301=P2/285

P2= 3.0 atm (3.0299003322 rounded to 2 sig figs)

8 0

4 years ago

Read 2 more answers

Calculate the pH during the titration of 20.00 mL of 0.1000 M HNO2(aq) with 0.1000 M KOH(aq) after 13.27 mL of the base have bee

Slav-nsk [51]

Answer:

pH = 2.462.

Explanation:

Hello there!

In this case, according to the reaction between nitrous acid and potassium hydroxide:

$HNO_2+KOH\rightarrow KNO_2+H_2O$

It is possible to compute the moles of each reactant given their concentrations and volumes:

$n_{HNO_2}=0.02000L*0.1000mol/L=2.000x10^{-3}mol\\\\n_{KOH}=0.1000mol/L*0.01327L=1.327x10^{-3}mol$

Thus, the resulting moles of nitrous acid after the reaction are:

$n_{HNO_2}=2.000x10^{-3}mol-1.327x10^{-3}mol=6.73x10^{-4}mol$

So the resulting concentration considering the final volume (20.00mL+13.27mL) is:

$[HNO_2]=\frac{6.73x10^{-4}mol}{0.01327L+0.02000L} =0.02023M$

In such a way, we can write the ionization of this weak acid to obtain:

$HNO_2+H_2O\rightleftharpoons NO_2^-+H_3O^+$

So we can set up its equilibrium expression to obtain x as the concentration of H3O+:

$Ka=\frac{[NO_2^-][H_3O^+]}{[HNO_2]}\\\\7.1x10^{-4}=\frac{x^2}{0.02023M-x}$

Next, by solving for the two roots of x, we get:

$x_1=-0.004161M\\\\x_2=0.003451M$

Whereas the correct value is 0.003451 M. Finally, we compute the resulting pH:

$pH=-log(0.003451)\\\\pH=2.462$

Best regards!

4 0

3 years ago

Bromine (Br2) is produced by reacting HBr with O2, with water as a byproduct. The O2 is part of an air (21 mol % O2, 79 mol % N2

Karolina [17]

Answer:

The mole fractions:

$x_{HBr}=\frac{100mol}{318.5}=0.314$

$x_{Br_2}=\frac{78mol}{318.5}=0.245$

$x_{H_2O}=\frac{78mol}{318.5}=0.245$

$x_{O_2}=\frac{62.5mol}{318.5}=0.196$

Explanation:

The reaction described is:

$2 HBr (g) + 1/2 O_2 (g) \longrightarrow Br_2 (g) + H_2O (g)$

The limiting reactant is the HBr (oxygen is in excess).

a) The mass (in moles) balance for this sistem:

$n_{Br_2}=\frac{ 1 mol Br_2}{1 mol HBr} *n_{HBr}*0.78$

(the 0.78 is because of the fractional conversion)

$n_{O_2}=\frac{ 0.5 mol O_2}{1 mol HBr} *n_{HBr}*1.25$

(the 1.25 is because of the oxygen excess)

$n_{H_2O}=\frac{ 1 mol H_2O}{1 mol Br_2} *n_{Br_2}$

There is only one degree of freedom in this sistem, you can either deffine the moles of HBr you have or the moles of Br2 you want to produce. The other variables are all linked by the equations above.

b) Base of calculation 100 mol of HBr:

$nn_{HBr}=100 mol HBr$

$n_{Br_2}=\frac{ 1 mol Br_2}{1 mol HBr} *100mol HBr*0.78$

$n_{Br_2}=78 mol Br2$

$n_{O_2}=\frac{ 0.5 mol O_2}{1 mol HBr} *100 mol HBr*1.25$

$n_{O_2}=62.5 mol O_2$

$n_{H_2O}=n_{Br_2}= 78 mol$

$n_{total}=(78+78+100+62.5)mol= 318.5mol$

The mole fractions:

$x_{HBr}=\frac{100mol}{318.5}=0.314$

$x_{Br_2}=\frac{78mol}{318.5}=0.245$

$x_{H_2O}=\frac{78mol}{318.5}=0.245$

$x_{O_2}=\frac{62.5mol}{318.5}=0.196$

4 0

3 years ago

What are The advantages of using scientific procedures in doing science experiments?

Studentka2010 [4]

Answer:

Doing experiments by scientific procedures is advantageous and helpful.

Explanation:

The scientific procedure should be followed while performing a experiment as it has many advantages like:

Working in safe environment: Performing a experiment by scientific procedure ensures the safety of the experimenter.

It reduces the chances of mistakes: The proper availability of the scientific equipment helps in reduction of the chances of the mistakes.

A sequence of steps is followed: A proper sequence of steps is followed to perform a experiment step by step. Performing experiment without scientific procedure may cause the experimenter to forgot a step.

More Accuracy: The readings of the experiment is more accurate by doing experiment by scientifically.

Chemical changes can be observed: The physical and chemical changes can be observed and can be measured by the lab equipment to perform more accurately.

less chance of risks: Performing in the safe scientific environment and using proper safety equipment reduces the chances of risks to the experimenter.

5 0

3 years ago