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3 years ago

Which chemical equation shows that the total mass during a chemical reaction stays the same?

Chemistry

2 answers:

k0ka [10]3 years ago

5 0

Answer:

Option A) Mg + Cl₂ → MgCl₂

Explanation:

The law of conservation of mass is guaranteed in a chemical equation. Since the mass of the atoms do not change, that means that the number of each kind of atoms in the reactant side is equal to the number of atoms of the same kind in the product side.

The first equation is:

A) Mg + Cl₂ → MgCl₂

Number of atoms:

atom Reactant side Product side

Mg 1 1

Cl 2 2

Therefore, the table displays that there are the same number of atoms of each kind on both sides, showing that the total mass during the chemical reaction stays the same.

B) NaOH + MgCl₂ → NaCl + MgOH

This equation displays 2 atoms of Cl on the left side and 1 atom of Cl on the right side; thus, it is not showing that the total mass stays the same during the chemical reaction.

C) 2Na + 2H₂O → NaOH + H₂

Neither the sodium, nor oxygen, nor hydrogen atoms are balanced. Thus, this does not show that the total mass stays the same.

D) H₂O + O₂ → H₂O

The reactant side contains 3 oxygen atoms and the product side contains 1 atoms of oxygen; thus, this is not balanced: it does not show that the total mass stays de same during the chemical reaction.

Triss [41]3 years ago

4 0

Answer:

Explanation:

Mg + Cl2 → MgCl2 obeys the law of conservation of mass since the same number of each type of atom appears on both sides of the reaction.

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When an aqueous solution of AgNO3 is electrolyzed, a gas is observed to form at the anode. The gas is

iris [78.8K]

Answer:

Oxygen

Explanation:

First, list out all the ions in the aqueous solution:

Ag+, NO3-

H+, OH-

In the anode, the substance lose electrons to undergo oxidation.

From the 4 ions, only OH- can lose electrons to form water and oxygen,

4OH- ---> O2 + 2H2O + 4e-

While others tend to gain electrons to form new substances instead (they undergo reduction).

Oxygen is the gas produced.

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3 years ago

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2 years ago

A barrel of crude oil has a volume of 42 gallons, only approximately 45% of which is processed into gasoline. If your car achiev

balandron [24]

Answer:

The number of barrels of crude oil required to run the car for a year is 52.9 barrels of crude oil

Explanation:

The information given are as follows;

Percentage of crude oil processed into gasoline = 45%

Distance achieved per gallon by car = 36 mi/gal

Distance driven per year = 36,000 miles

$Gasoline\, usage \, in \, one \, year = \dfrac{Distance \ driven\ per \ year }{Distance\ achieved \ per gallon \ by \ car } = \dfrac{36000\, miles}{36\, miles/gallon}$ $\dfrac{36000\, miles}{36\, miles/gallon} = 1000 \, gallons$

∴ Gasoline usage in one year = 1,000 gallons

Percentage of crude oil processed into gasoline = 45%

Hence, where 45% of the crude oil produces 1000, the volume of crude, x, from which the gasoline is sourced becomes;

x × 45/100 = 1000 gallons

x =100 × 1000/45 = 20000/9 gallons of crude

1 barrel of crude oil is approximately 42 gallons of crude oil

∴ 20000/9 gallons of crude = 20000/(9×42) barells of crude = 10000/

Which gives;

$52\tfrac{172}{189} \, barrels \, of \, crude \, oil$

Which is 52.9 barrels of crude oil

Hence the number of barrels of crude oil required to run the car for a year = 52.9 barrels of crude oil.

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3 years ago

1. Methane (CH4) combusts as shown in the equation below. If 3 moles of methane were used in the combustion, what would be the c

umka2103 [35]

Answer:

The change in enthalpy in the combustion of 3 moles of methane = -2406 kJ

Explanation:

Step 1: The balanced equation

CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g) ΔH = -802 kJ

Step 2: Given data

We notice that for 1 mole of methane (CH4), we need 2 moles of O2 to produce : 1 mole of CO2 and 2 moles of H20.

The enthalpy change of combustion, given here as Δ H , tells us how much heat is either absorbed or released by the combustion of one mole of a substance.

In this case: we notice that the combustion of 1 mole of methane gives off (because of the negative number), 802.3 kJ of heat.

Step 3: calculate the enthalpy change for 3 moles

The -802 kj is the enthalpy change for 1 mole

The change in enthalpy for 3 moles = 3* -802 kJ = -2406 kJ

The change in enthalpy in the combustion of 3 moles of methane = -2406 kJ

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3 years ago

Which ion has a charge of 2-?

nataly862011 [7]

Answer:

Explanation:

More electrons than protons, thus giving the atom an overall charge of -2

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3 years ago