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3 years ago

What is a kilogram??

Chemistry

2 answers:

sukhopar [10]3 years ago

8 0

A kilogram is a measure of mass; 1,000 grams

____ [38]3 years ago

8 0

A kilogram is a unit of measurement

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Consider the molecular structure for linuron, an herbicide, provided in the questions below. How many pi bonds are in the molecu

Sophie [7]

In the herbicide linuron whose structure is shown in the image attached, there are four pi bonds.

A pi bond is formed by a sideways overlap of atomic orbitals. A sigma bond is formed by an end to end or head to head overlap of atomic orbitals. Pi bonds lead to the occurrence of multiple bonds in the molecule.

In the herbicide linuron whose structure is shown in the image attached to this answer, there are four pi bonds which are easily spotted as double bonds in the structure.

Learn more: brainly.com/question/7291190

6 0

2 years ago

What does chemistry have to do with drug testing

diamong [38]

Answer:

Forensic drug chemists analyze samples of unknown materials including powders, liquids and stains to determine the chemical identity or characteristics of the compounds that make up the sample. samples submitted as evidence in a drug-related case can contain one compound or a mixture of many compounds.

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3 years ago

What is the pH at the equivalence point in the titration of a 25.7 mL sample of a 0.370 M aqueous nitrous acid solution with a 0

expeople1 [14]

Answer:

pH = 8.24

Explanation:

Nitrous acid (HNO₂) reacts with KOH, thus:

HNO₂ + KOH → KNO₂ + H₂O

Moles of HNO₂ are:

0.0257mL ₓ (0.370mol / L) = 0.00951moles.

In equivalence point, the complete moles of nitrous acid reacts with KOH producing potassium nitrite. There are needed:

0.00951mol ₓ (1L / 0.491mol) = 0.01937L ≡ 19.4mL of 0.491M KOH to reach equivalence point.

Total volume in equivalence point is: 19.4mL + 25.7mL = 45.1mL

Potassium nitrite is in equilibrium with water, thus:

NO₂⁻ + H₂O ⇄ HNO₂ + OH⁻

Where equilibrium constant, Kb, is defined as:

Kb = 1.41x10⁻¹¹ = $\frac{[OH^-][HNO_2]}{[NO_2]}$

In equilibrium, molarity of each compound are:

[NO₂⁻]: 0.00951mol/0.00451L - X = 0.211M - X

[HNO₂]: X

[OH⁻]: X

Where X is reaction coordinate

Replacing in Kb:

1.41x10⁻¹¹ = $\frac{[X][X]}{[0.211 -X]}$

0 = X² + 1.41x10⁻¹¹X - 2.97x10⁻¹²

Solving for X:

X = -1.72x10⁻⁶ FALSE ANSWER. There is no negative concentrations.

X = 1.72x10⁻⁶. Right answer.

That means:

[OH⁻]: 1.72x10⁻⁶M

As pOH is -log [OH⁻] and pH = 14-pOH:

pOH = 5.76; pH = 8.24

3 0

3 years ago

A 50.0 mL graduated cylinder has a mass of 65.1 g. When it is filled with an unknown liquid to the 49.3 mL mark, the cylinder an

Delvig [45]

Answer: The density of liquid is $1.12g/cm^3$

Explanation:

We are given:

Mass of cylinder, $m_1$ = 65.1 g

Mass of liquid and cylinder combined, M = 120.5 g

Mass of liquid, $m_2$ = $(M-m_1)=(120.5-65.1)g=55.4g$

To calculate density of a substance, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

We are given:

Mass of liquid = 55.4 g

Volume of liquid = 49.3 mL = $49.3 cm^3$ (Conversion factor: $1mL=1cm^3$ )

Putting values in above equation, we get:

$\text{Density of liquid}=\frac{55.4g}{49.3cm^3}\\\\\text{Density of liquid}=1.12g/cm^3$

Hence, the density of liquid is $1.12g/cm^3$

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3 years ago

What do the elements within a "period" have in common? (pick one)

Gnesinka [82]

Answer:

All of the elements in a period have the same number of atomic orbitals. For example, every element in the top row (the first period) has one orbital for its electrons. All of the elements in the second row (the second period) have two orbitals for their electrons.

Explanation:

6 0

2 years ago

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