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3 years ago

How many significant figures are in the quantity 12.0 mL? O A. 1 B. 2 C. 3 O D. 12

Chemistry

1 answer:

insens350 [35]3 years ago

7 0

Answer:

C. 3

Explanation:

12.0 - 3 significant figures 1,2 and 0, because 0 is after decimal point.

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Scientists have shown that in our solar system, the planets orbit the sun. Which of the following BEST explains why the planets

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Answer:

Explanation:

The sun is larger than the planets in our solar system and has far more mass and gravity than the planets.

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3 years ago

For this ionic compound, what would be the name of the anion? Ca(NO3)2

Ne4ueva [31]

Idk if it's correct but I guess it's calcite (c)

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4 years ago

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Find the enthalpy of neutralization of HCl and NaOH. 137 cm3 of 2.6 mol dm-3 hydrochloric acid was neutralized by 137 cm3 of 2.6

liraira [26]

Answer : The correct option is, (D) 89.39 KJ/mole

Explanation :

First we have to calculate the moles of HCl and NaOH.

$\text{Moles of HCl}=\text{Concentration of HCl}\times \text{Volume of solution}=2.6mole/L\times 0.137L=0.3562mole$

$\text{Moles of NaOH}=\text{Concentration of NaOH}\times \text{Volume of solution}=2.6mole/L\times 0.137L=0.3562mole$

The balanced chemical reaction will be,

$HCl+NaOH\rightarrow NaCl+H_2O$

From the balanced reaction we conclude that,

As, 1 mole of HCl neutralizes by 1 mole of NaOH

So, 0.3562 mole of HCl neutralizes by 0.3562 mole of NaOH

Thus, the number of neutralized moles = 0.3562 mole

Now we have to calculate the mass of water.

As we know that the density of water is 1 g/ml. So, the mass of water will be:

The volume of water = $137ml+137ml=274ml$

$\text{Mass of water}=\text{Density of water}\times \text{Volume of water}=1g/ml\times 274ml=274g$

Now we have to calculate the heat absorbed during the reaction.

$q=m\times c\times (T_{final}-T_{initial})$

where,

q = heat absorbed = ?

$c$ = specific heat of water = $4.18J/g^oC$

m = mass of water = 274 g

$T_{final}$ = final temperature of water = 325.8 K

$T_{initial}$ = initial temperature of metal = 298 K

Now put all the given values in the above formula, we get:

$q=274g\times 4.18J/g^oC\times (325.8-298)K$

$q=31839.896J=31.84KJ$

Thus, the heat released during the neutralization = -31.84 KJ

Now we have to calculate the enthalpy of neutralization.

$\Delta H=\frac{q}{n}$

where,

$\Delta H$ = enthalpy of neutralization = ?

q = heat released = -31.84 KJ

n = number of moles used in neutralization = 0.3562 mole

$\Delta H=\frac{-31.84KJ}{0.3562mole}=-89.39KJ/mole$

The negative sign indicate the heat released during the reaction.

Therefore, the enthalpy of neutralization is, 89.39 KJ/mole

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4 years ago

Write the chemical equation for the reaction of Fe(II) ion (Fe2 ) with phenanthroline. (Use the abbreviation phen for the phenan

miskamm [114]

Answer:

[Fe(phen)3]2+ Reactants Fe+2 clear phen white solid product orange red

mol ratios 1;1 OF fE

Explanation:

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3 years ago

You are performing an experiment in a lab to attempt a new method of producing pure elements from compounds. The only problem is

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You need to calculate the atomic weight of that element.

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atomic weight = 209.1 / 3 = 69.7 g/mol

The element produced will be gallium, Ga.

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4 years ago

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