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3 years ago

Which of the following is true regarding the law of conservation of mass

1 answer:

3 0

These are the answer options of this question and the comments about their validity:

A) It dictates that the number of molecules on each side of a chemical equation must be the same.

False: the number of molecules can change. Take this simple reaction for example:

2H2(g) + O2 -> 2H2O

You start with 3 molecules, 2 molecules of H2 and 1 molecule of O2, and end with 2 molecules of water. Then the number of molecules of each side is different.

B) It dictates that the number of atoms of each element must be the same on both sides of a chemical equation.

TRUE: in a chemical reaction the atoms remain being the same at start and at the end of the process. Given that each atom has a characteristic mass, their conservation implies the law of conservation mass.

C) It states that the mass of the reactants must remain constant in order for a chemical reaction to proceed.

FALSE. The mass of the reactants changes during a chemical reaction, while they transform into the products.

D) It does not apply to chemical reactions.

FALSE: It is an important law used in the calculus related with chemical reactions.

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What volumes of 0.200 M HCOOH and 2.00 M NaOH would make 500. mL of a buffer with the same pH as one made from 475 mL of 0.200 M

Fed [463]

36 ml of NaOh and 464 ml of HCOOH would be enough to form 500 ml of a buffer with the same pH as the buffer made with benzoic acid and NaOH.

What is benzoic acid found in?

Some natural sources of benzoic acid include: Fruits: Apricots, prunes, berries, cranberries, peaches, kiwi, bananas, watermelon, pineapple, oranges.
Spices: Cinnamon, cloves, allspice, cayenne pepper, mustard seeds, thyme, turmeric, coriander.

Calculate the amount of moles in NaOH and benzoic acid. This calculation is done by multiplying molarity by volume.

Amount of moles of NaOH -2 × 0.025 = 0.05 mol

Amount of moles of benzoic acid 2 × 0.475 = 0.095 mol

In this case, we can calculate the pH produced by the buffer of these two reagents, as follows

$pH = pKa + log\frac{base}{acid}$

$4.2 + log\frac{0.05}{0.045} = 4.245$

We must repeat this calculation, with the values shown for HCOOH and NaOH. In this case, we can calculate as follows

$pH = pKa + log\frac{base}{acid}$

$4.245 = 3.75 + log\frac{base}{acid}$

$log\frac{base}{acid} = 0.5$

$\frac{base}{acid} = 3.162$

Now we must solve the equation above. This will be done using the following values

$\frac{2(0.5 - x)}{0.2x - 2(0.5 - x)} = 0.464 L$

With these values, we can calculate the volumes of NaOH and HCOOH needed to make the buffer.

NaOH volume

( 0.5 - 0.464)L

0.036L .................... 36ml

HCOOH volume

500 - 36 = 464mL

Learn more about benzoic acid

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3 0

2 years ago

Arrange the following elements in order of decreasing metallic character.

Ivenika [448]

The arrangement of the elements in order of decreasing metallic character is: Rb, Zn, P, S, F, Ca, Co, Cr

<h3 /><h3>What are metals?</h3>

Metals are elements which are known by their special ability to form ions by a loss of electrons.

The increasing metallic character of metal is a measure of their ability to lose electrons.

Metallic character increases from right to left and down a group in the period table.

Metals are found to the left of the period table.

In conclusion, metals are known by their ability to lose electrons.

Learn more about metals at: brainly.com/question/25597694

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8 0

2 years ago

2C 2 H 6 +7O 2 ***>4CO 2 +6H 2 O if 7.0 g of C 2 H 6 react with 18 g of O 2 , how many grams of water will be produced

Alex787 [66]

Answer:

grams H₂O produced = 8.7 grams

Explanation:

Given 2C₂H₆(g) + 7O₂(g) => 4CO₂(g) + 6H₂O(l)

7g 18g ?g

Plan => Convert gms to moles => determine Limiting reactant => solve for moles water => convert moles water to grams water

Moles Reactants

moles C₂H₆ = 7g/30g/mol = 0.233mol

moles O₂ = 18g/32g/mol = 0.563mol

Limiting Reactant => (Test for Limiting Reactant) Divide mole value by respective coefficient of balanced equation; the smaller number is the limiting reactant.

moles C₂H₆/2 = 0.233/2 = 0.12

moles O₂/7 = 0.08

Limiting Reactant is O₂

Moles and Grams of H₂O:

Use Limiting Reactant moles (not division value) to calculate moles of H₂O.

moles H₂O = 6/7(moles O₂) = 6/7(0.562) moles H₂O = 0.482 mole H₂O yield

grams H₂O = (0.482mol)(18g·mol⁻¹) = 8.7 grams H₂O

3 0

3 years ago

What is the balanced equation if electrolysis?

ra1l [238]

Answer:

It's Al 3+ + 3e - → Al

Explanation:

Because three negatively charged electrons are needed to balance the three positive charges on the aluminum ion

5 0

2 years ago

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In which region is the substance in both the solid phase and the liquid phase ?

sergiy2304 [10]

Answer: Region 3

Explanation: The temperature and time graph suggests that region 3 is the region in which the substance can co exist in both the phases that is solid phase and liquid phase.

Region 1 explains that the the solid has just started melting and there occurs a break point and then region 2 again explains that the solid is taking more time with temperature to get converted into the liquid and thus region 3 explains the equilibrium between the two phases.

3 0

3 years ago

Read 2 more answers