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4 years ago

Atoms of which element react spontaneously with mg2+ (aq)?

1 answer:

3 0

The complete answer contains the answer choices.

This is the complete question:

Atoms of which element react spontaneously with Mg2+(aq)? (1)chromium
(2)barium
(3)iron
(4)zinc

Answer: option 2. barium.

Explanation.

1) Mg ²⁺ (aq) is the aquous cation of the metal Mg.

2) Only a metal more reactive than Mg will be able to exchange with it the oxidation states.

3) Mg is an earth alkalyne metal (group 2 of the periodic table). The metals from this group are more reactive than the metals in the groups to its right: 3, 4, 5, 6, 7, ... Only the alkalyne metals (those in group 1) are more reactive than the earth alkalyne metals.

4) Of the list, barium is the only alkalyne metal, so it is more reactive than Mg and will be able to deliver 2 electrons to transform the cations Mg²⁺ into Mg while the very Ba will become Ba²⁺.

5) Chromium, iron and zinc are transition metals, so less metallic (reactive) than Mg.

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1) A light bulb takes in 30 of energy per second. It transfers 3j as use

natta225 [31]

Answer:

$\boxed{\text{10 \%}}$

Explanation:

The formula for efficiency is

$\begin{array}{rcl}\text{Efficiency} & = & \dfrac{\text{useful energy out}}{\text{energy in}} \times 100 \,\% \\\\\eta & = & \dfrac{w_{\text{out}}}{w_{\text{in}} } \times 100 \,\%\\\end{array}$

Data:

Useful energy = 3 J

Energy input = 30 J

Calculation:

$\begin{array}{rcl}\eta & = & \dfrac{\text{3 J}}{\text{30 J}} \times 100 \,\%\\\\\eta & = & 10 \, \%\\\end{array}\\\text{ The efficiency is }\boxed{\textbf{10 \%}}$

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3 years ago

Classify the following reaction.

Klio2033 [76]

Answer:

Explanation:

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7 0

3 years ago

Calcium carbonate is often used as an antacid. Your stomach acid is composed of HCl at a pH of 1.5. If you ate toooo much Turkey

stiks02 [169]

<u>Answer:</u> 0.0237 g of calcium carbonate would be required to neutralize the given amount of HCl

<u>Explanation:</u>

pH is defined as the negative logarithm of hydrogen ion concentration present in the solution

$pH=-\log [H^+]$ .....(1)

Given value of pH = 1.5

Putting values in equation 1:

$1.5=-\log[H^+]$

$[H^+]=10^{(-1.5)}=0.0316M$

Molarity is defined as the amount of solute expressed in the number of moles present per liter of solution. The units of molarity are mol/L. The formula used to calculate molarity:

$\text{Molarity of solution}=\frac{\text{Number of moles of solute}\times 1000}{\text{Volume of solution (mL)}}$ .....(2)

We are given:

Volume of solution = 15.0 mL

Molarity of HCl = 0.0316 M

Putting values in equation 2:

$0.0316=\frac{\text{Moles of HCl}\times 1000}{15.0}\\\\\text{Moles of HCl}=\frac{0.0316\times 15.0}{1000}=4.74\times 10^{-4}mol$

The chemical equation for the reaction of HCl and calcium carbonate follows:

$2HCl+CaCO_3\rightarrow H_2CO_3+CaCl_2$

By the stoichiometry of the reaction:

2 moles of HCl reacts with 1 mole of calcium carbonate

So, $4.74\times 10^{-4}mol$ of HCl will react with = $\frac{1}{2}\times 4.74\times 10^{-4}=2.37\times 10^{-4}mol$ of calcium carbonate

The number of moles is defined as the ratio of the mass of a substance to its molar mass.

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Moles of calcium carbonate = $2.37\times 10^{-4}mol$

Molar mass of calcium carbonate = 100.01 g/mol

Putting values in the above equation:

$\text{Mass of }CaCO_3=(2.37\times 10^{-4}mol)\times 100.01g/mol\\\\\text{Mass of }CaCO_3=0.0237g$

Hence, 0.0237 g of calcium carbonate would be required to neutralize the given amount of HCl

7 0

3 years ago

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Answer:

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Explanation:

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3 years ago

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nirvana33 [79]

(Missing in the question) solubility in g per 100 mL of water:
CdI2 86.2 (cold water) so,
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