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2 years ago

Wy do rough, uneven pebbles become smooth and rounded

Chemistry

1 answer:

NeTakaya2 years ago

4 0

Answer:

Due to erosion

Explanation:

When a pebble breaks off from a greater piece it is rough. After being weathered down and constantly hit against by other masses, the side will wear down and smoothen out

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Calculate the pH of a solution that is 0.210 M in nitrous acid (HNO2) and 0.290 M in potassium nitrite (KNO2). The acid dissocia

jeka94

Answer:

pH = 3.49

Explanation:

We have a buffer system formed by a weak acid (HNO₂) and its conjugate base (NO₂⁻ coming from KNO₂). We can calculate the pH of a buffer ssytem using the Henderson-Hasselbach equation.

pH = pKa + log [base] / [acid]

pH = -log Ka + log [NO₂⁻] / [HNO₂]

pH = -log 4.50 × 10⁻⁴ + log 0.290 M / 0.210 M

pH = 3.49

6 0

3 years ago

People take antacids, such as milk of magnesia, to reduce the discomfort of acid stomach or heartburn. The recommended dose of m

Llana [10]

Answer:

$V_{HCl}=0.208L=208mL$

Explanation:

Hello,

In this case, since the chemical reaction is:

$2HCl+Mg(OH)_2\rightarrow MgCl_2+2H_2O$

We can see that hydrochloric acid and magnesium hydroxide are in a 2:1 mole ratio, which means that the neutralization point, we can write:

$n_{HCl}=2*n_{Mg(OH)_2}$

In such a way, the moles of magnesium hydroxide (molar mass 58.3 g/mol) in 500 mg are:

$n_{Mg(OH)_2}=500mg*\frac{1g}{1000mg}*\frac{1mol}{58.3g} =0.00858mol$

Next, since the pH of hydrochloric acid is 1.25, the concentration of H⁺ as well as the acid (strong acid) is:

$[H^+]=[HCl]=10^{-pH}=10^{-1.25}=0.0562M$

Then, since the concentration and the volume define the moles, we can write:

$[HCl]*V_{HCl}=2*n_{Mg(OH)_2}$

Therefore, the neutralized volume turns out:

$V_{HCl}=\frac{2*0.00858mol}{0.0562\frac{mol}{L} }\\ \\V_{HCl}=0.208L=208mL$

Best regards.

3 0

2 years ago

How many grams of O are in 635 g of Li 2 O ?

KiRa [710]

Answer:

340g

Explanation:

Lithium oxide or Li2O is an inorganic compound made of two lithiums and one oxygen molecules. Lithium molecular mass is 6.94g/mol while oxygen molecular mass is 16g/mol. The molecular mass of Li2O will be:

2* 6.94g/mol + 1*16g/mol= 29.88g/mol

Out of 1 mol lithium oxide (29.88g), there is 1 mol of oxygen(16g). Then, out of 635g lithium oxide the number of oxygen will be: 635g * (16g/29.88g)= 340g

5 0

2 years ago

The arrangement of elements based on their properties

Thepotemich [5.8K]

<span>The arrangement of the periodic table leads us to visualize certain trends among the atoms. The vertical columns ( basically their groups) of the periodic table and they are arranged such that all its elements have the same number of valence electrons. And all the elements within a certain group thus share similar properties and that's about it.</span>

4 0

3 years ago

Determine the mass (in grams) of 8.02 x 1024 atoms of mercury (Hg).

Virty [35]

<h3>Answer:</h3>

2670 g Hg

<h3>General Formulas and Concepts: </h3>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right

<u>Chemistry</u>

<u>Atomic Structure</u>

Reading a Periodic Table
Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

<u>Stoichiometry</u>

Using Dimensional Analysis

<h3>Explanation: </h3>

<u>Step 1: Define</u>

8.02 × 10²⁴ atoms Hg

<u>Step 2: Identify Conversions</u>

Avogadro's Number

Molar Mass of Hg - 200.59 g/mol

<u>Step 3: Convert</u>

Set up: $\displaystyle 8.02 \cdot 10^{24} \ atoms \ Hg(\frac{1 \ mol \ Hg}{6.022 \cdot 10^{23} \ atoms \ Hg})(\frac{200.59 \ g \ Hg}{1 \ mol \ Hg})$
Divide/Multiply: $\displaystyle 2671.42 \ g \ Hg$

<u>Step 4: Check</u>

<em>Follow sig fig rules and round. We are given 3 sig figs.</em>

2671.42 g Hg ≈ 2670 g Hg

3 0

3 years ago