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2 years ago

6

A chemist is looking at an electrically neutral atom that has three valence electrons. If she knows the element is a metalloid,

which one (or ones) is it?

1 answer:

Rus_ich [418]2 years ago

8 0

Your answer is boron,

I looked at the periodic table, there is nothing else that falls under this specs.

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How many sulfur atoms are in 3.7 mol of SO2?<br><br> × 10 S atoms

Allisa [31]

Answer: 22.3 *10^23 S atoms

Explanation:

8 0

2 years ago

Using the equations 2 Sr(s) + O₂ (g) → 2 SrO (s) ∆H° = -1184 kJ/mol SrO (s) + CO₂ (g) → SrCO₃ (s) ∆H° = -234 kJ/mol CO₂ (g) → C(

kkurt [141]

<u>Answer:</u> The $\Delta H^o_{rxn}$ for the reaction is 72 kJ.

<u>Explanation:</u>

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction follows:

$2SrCO_3(s)\rightarrow 2Sr(s)+2C(s)+3O_2(g)$ $\Delta H^o_{rxn}=?$

The intermediate balanced chemical reaction are:

(1) $2Sr(s)+O_2(g)\rightarrow 2SrO(s)$ $\Delta H_1=-1184kJ$

(2) $SrO(s)+CO_2(g)\rightarrow SrCO_3(s)$ $\Delta H_2=-234kJ$ ( × 2)

(3) $CO_2(g)\rightarrow C(s)+O_2(g)$ $\Delta H_3=394kJ$ ( × 2)

The expression for enthalpy of the reaction follows:

$\Delta H^o_{rxn}=[1\times (\Delta H_1)]+[2\times (-\Delta H_2)]+[2\times (\Delta H_3)]$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(1\times (-1184))+(2\times -(-234))+(2\times (394))]=72kJ$

Hence, the $\Delta H^o_{rxn}$ for the reaction is 72 kJ.

4 0

2 years ago

What can you conclude about these two reactions based on the chemical equations? Reaction A: 6CO2(g) + 6H2O(l) + sunlight ? C6H1

OlgaM077 [116]

Given reactions:

(A) 6CO2(g) + 6H2O(l) + sunlight → C6H12O6(aq) + 6O2(g)

(B) 2H2(g) + O2(g) → 2H2O(g) + energy

Exothermic reactions are those which proceed with the release of heat/energy. In contrast, endothermic reactions proceed with the absorption of energy in the form of heat or light.

Since reaction A required sunlight, it is endothermic. Reaction B releases energy, hence exothermic

Ans: (B)

A is endothermic

B is exothermic

8 0

2 years ago

The three states of matter differ primarily in terms of shape and volume. Describe solids, liquids and gases in these terms.

schepotkina [342]

Answer:

solids have definite shape and volume. liquid have definite volume but not definite shape. gases do not have definite volume as well as definite shape.

8 0

2 years ago

Quinine, an antimalarial drug, is 8.63% nitrogen. There are two nitrogen atoms per molecule. What is the molecular weight of qui

Furkat [3]

Answer:

324.18 g/mol

Explanation:

Let the molecular mass of the antimalarial drug, Quinine is x g/mol

According to question,

Nitrogen present in the drug is 8.63% of x

So, mass of nitrogen = $\frac {8.63}{100}\times x$

Also, according to the question,

2 atoms are present in 1 molecule of the drug.

Mass of nitrogen = 14.01 amu = 14.01 g/mol (grams for 1 mole)

So, mass of nitrogen = 14.01×2 = 28.02

These 2 must be equal so,

$\frac {8.63}{100}\times x=28.02$

solving for x, we get:

<u>x = 324.18 g/mol</u>

6 0

3 years ago