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3 years ago

Which of the following are true statements about chemical formulas?

Chemistry

2 answers:

ludmilkaskok [199]3 years ago

7 0

Answer:

A;3 B;8

Explanation:

Elena-2011 [213]3 years ago

5 0

Answer:

The number of atoms or ions in a compound are shown as subscripts in the chemical formula.

If a compound's ions have a different value, then the chemical formula should have subscripts.

Explanation:

So let's say we have Mg²⁺ (cation) and Cl⁻ (anion).

Mg²⁺ and Cl⁻

As you can see they do not have balanced charges. We need to balance out the charges, so to match the 2+ charge of one Mg, we need two Cl⁻ ions.

Now that we know this, we can write the chemical formula. When you write the chemical formula, you put the cation first before the anion. DO NOT PUT THE CHARGES in the formula.

MgCl

But like we said earlier, we will need two Cl ions to balance this out. To indicate the number of atoms, you will write the number of atoms as a subscript.

Notice that the ions involved are of different value, there is only 1 Mg ion and 2 Cl ions. If they are not the same, you write the subscript. But if they are the same, there is no need.

The conventional method of writing a chemical formula is to not put subscripts if their values are the same.

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Discover a good rule for making the center of the atom “stable.” What seems to make the center of the

nasty-shy [4]

Answer: Atoms that have lost or gained electrons and are now charged (different number of electrons). By putting the correct amount of protons and neutrons in the center, and you cannot have more than 2 protons/neutrons than the other if you want it to be stable. The number of protons determines the name of the element.

4 0

4 years ago

Read 2 more answers

Fe2+(s) + Cr6+(aq) → Fe3+(aq) + Cr3+(aq)

Komok [63]

Explanation:

A. Cr reduced

B. Fe oxidized

C. Fe reducing agent

D. Cr oxidizing agent

3 0

2 years ago

Read 2 more answers

The standard molar enthalpy of formation of NH3(g) is -45.9 kJ/mol. What is the enthalpy change if 9.51 g N2(g) and 1.96 g H2(g)

Vladimir [108]

Answer:

$\Delta H=-29.7kJ$

Explanation:

Hello!

In this case, since the undergoing chemical reaction is:

$N_2+3H_2\rightarrow 2NH_3$

We first need to identify the limiting reactant given the masses of nitrogen and hydrogen:

$n_{NH_3}^{by\ H_2}=1.96gH_2*\frac{1molH_2}{2.02gH_2}*\frac{2molNH_3}{3molH_2}=0.647molNH_3\\\\ n_{NH_3}^{by\ N_2}=9.51gN_2*\frac{1molN_2}{28.02gN_2}*\frac{2molNH_3}{1molN_2}=0.679molNH_3$

It means that only 0.647 moles of ammonia are yielded, so the resulting enthalpy change is:

$\Delta H=0.647molNH_3*\frac{-45.9kJ}{1molNH_3}\\\\ \Delta H=-29.7kJ$

Best regards!

3 0

3 years ago

Explain how Beer’s law can be applied in food, drug or medical testing

KonstantinChe [14]

<h2>Answer with explanation:</h2>

<em><u>Beer's Law is described as if a light passes from a solution, the concentration of the solution is directly proportional to the absorbance of light by that solution.</u></em>

Every element has a definite of absorbance of light.

In the testing of food, drugs or in medical testing, the light is passed from the sample.

Them transmitted light from these samples are measured. The difference between target light amount and transmitted light is the amount of absorbed light.

From this absorbed light value, we can identify an element in sample and its quantity.

Spectrophometry is based on this law.

8 0

3 years ago

Lewis structures for the perchlorate ion (ClO4−) can be drawn with all single bonds or with one, two, or three double bonds. Dra

Vanyuwa [196]

Answer:

The most important resonance structure is 4 (attached picture). Its bon order is $\frac{7}{4}$ or $1\frac{3}{4}$ .

Explanation:

A picture with 4 forms of the perchlorate structure is attached. The first structure has simple bonds. The second structure contains a double bond, the third structure has two double bonds and the fourth structure has three double bonds.

Formal charge = group number of the periodic table - number of bonds (number of bonding electrons / 2) - number of non-shared electrons (lone pairs)

The formal charges in the first structure is +3 in chlorine and -1 in oxygen.

The formal charges in the second structure is +2 in chlorine, -1 in oxygen and 0 in the double bond oxygen.

The formal charges in the third structure is +1 in chlorine, -1 in the single bond oxygens and 0 in the double bond oxygens.

The formal charges in the fourth structure is 0 in chlorine, -1 in the single bond oxygen and 0 in the double bond oxygens.

The most important resonance structure is given by:

Most atoms have 0 formal charge.

Lowest magnitude of formal charges.

If there is a negative formal charge, it's on the most electronegative atom.

Hence, the fourth structure is the mosr important.

The bond order of the structure is:

Total number of bonds: 7

Total number of bond groups: 4

Bond order= $\frac{7}{4} =1\frac{3}{4}$

5 0

3 years ago