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1 month ago

Imagine you are a detective examining a crime scene. You are trying to

Chemistry

2 answers:

castortr0y [2.7K]1 month ago

4 0

Answer:

C. strands of hair discovered at the scene.

Explanation:

By utilizing the strands of hair, you can retrieve the DNA of the individual involved. This will provide a clearer lead in resolving the case.

I hope this information is helpful....

Tems11 [2.4K]1 month ago

3 0

Answer:

C. Strands of hair located at the crime scene.

Explanation:

Strands of hair from the crime scene are highly valuable for identifying the perpetrator, as they allow for the extraction of the criminal's DNA through DNA fingerprinting techniques. The analysis involves looking at the chemical composition of the hair and obtaining DNA from the hair follicle. For DNA extraction, the hair samples need to have an attached follicle. Nuclear DNA can be effectively gathered from the hair's root, whereas hair that’s been cut without the follicle won’t be effective. The DNA can remain viable in hair for about 1,000 to 10,000 years.

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What is the net ionic equation of the reaction of mgso4 with sr(no3)2? express you answer as a chemical equation including phase

castortr0y [2750]

MgSO4 and Sr(NO3)2 are soluble, leading to the following ionic equation: Mg+2 + SO4-2 + Sr+2 + 2NO3-1 → Mg+2 + 2NO3-2 + SrSO4. Since SrSO4 is insoluble, we cancel out Mg and 2NO3 from both sides, resulting in the net ionic equation: SO4-2 + Sr+2 → SrSO4

6 0

13 days ago

Read 2 more answers

Which of the following air pollutants is correctly paired with one of its major effects?

alisha [2721]

Response:

The accurate choice is;

Sulfur oxides linked to acid precipitation

Details:

Sulfur oxide in the atmosphere interacts with oxygen, water, and other chemicals leading to the creation of acidic precipitation known as acid rain.

Sulfur oxides react with moisture in clouds to generate sulfuric acid as follows;

The sulfur gas undergoes initial oxidation

SO₂ + OH → HOSO₂

The subsequent step involves producing sulfur trioxide

HOSO₂ + O₂ → HO₂ + SO₃

Finally, sulfur trioxide reacts with water to yield sulfuric acid

SO₃ + H₂O → H₂SO₄ (aq).

3 0

16 days ago

A crystallographer measures the horizontal spacing between molecules in a crystal. The spacing is

castortr0y [2750]

Answer: The overall width of a crystal measures 1.65 mm.

Explanation:

Horizontal distance separating the two molecules is 16.5 nm.

Width of the $10^5$ molecules: $16.5 nm\times 10^5=16.5\times 10^5 nm$

$1 nm=10^{-6} mm$

The overall width of a crystal measured in millimeters= $16.5\times 10^5\times 10^{-6} mm=1.65 mm$

The overall width of a crystal is 1.65 mm.

7 0

1 month ago

Read 2 more answers

Cathodic protection of a metal pipe against corrosion usually entails __________.

VMariaS [2707]

Answer:

C. connecting an active metal to designate the pipe as the cathode in an electrochemical cell.

Explanation:

Cathodic protection involves a method to manage the accelerated corrosion of a metal surface by designating it as the cathode within an electrochemical cell. This is accomplished by attaching the protected metal to a more sacrificial metal, which acts as the anode.

This method helps to preserve the metal by introducing a highly reactive metal that serves as the anode, supplying free electrons. By adding these free electrons, the active metal gives up its ions, protecting the less reactive steel from corrosion.

3 0

1 month ago

66.667 mL of 3.000 M H2SO4 (aq) solution was neutralized by the stoichiometric amount of 4.000 M Al(OH)3 solution in a coffee cu

eduard [2520]

Answer:

$\large \boxed{\Delta_{\textbf{r}}H =\text{-4600 J$\cdot$ mol}^{-1}}$

Explanation:

This scenario is unrealistic since Al(OH)₃ is not soluble in water.

The question consists of two parts:

A. Stoichiometry — where we determine volumes, masses, and moles for the products

B. Calorimetry — where we assess the enthalpy of the reaction.

A. Stoichiometry

1. Determine the volume of Al(OH)₃

(a) The balanced chemical equation:

2Al(OH)₃ + 3H₂SO₄ ⟶ Al₂(SO₄)₃ + 6H₂O

M/V: 66.667

c/mol·L⁻¹: 4.000 3.000

(b) Moles of H₂SO₄

$\rm \text{66.667 mL H$_{2}$}SO_{4} \times \dfrac{\text{3.000 mmol H$_{2}$SO}_{4}}{\text{1 mL H$_{2}$SO}_{4}} = \text{200.00 mmol H$_{2}$SO}_{4}$

(c) Moles of Al(OH)₃

The molar ratio stands at 2 mmol Al(OH)₃: 3 mmol H₂SO₄

$\text{Moles of Al(OH)}_{3} = \text{200.00 mmol of H$_{2}$SO}_{4} \times \dfrac{\text{2 mmol Al(OH)}_{3}}{\text{3 mmol H$_{2}$SO}_{4}}\\\\= \text{133.33 mmol Al(OH)}_{3}$

(d) Volume of Al(OH)₃

$\text{Moles of Al(OH)}_{3} = \text{200.00 mmol of H$_{2}$SO}_{4} \times \dfrac{\text{1 mL Al(OH)}_{3}}{\text{4 mmol H$_{2}$SO}_{4}} = \text{50.000 mL Al(OH)}_{3}$

B. Calorimetry

This reaction has two energy exchanges.

q₁ = heat from the reaction

q₂ = heat used to heat the calorimeter

q₁ + q₂ = 0

nΔH + mCΔT = 0

Data:

Moles of Al₂(SO₄)₃ = 0.066 667 mol

C = 1.10 J°C⁻¹g⁻¹

T_initial = 22.3 °C

T_final = 24.7 °C

Calculations

(a) Mass of solution

Assume solutions are as dense as water (though not realistic).

Mass of sulfuric acid solution = 66.667 g

Mass of aluminium hydroxide solution = 50.000

TOTAL = 116.667 g

(b) ΔT

ΔT = T_final - T_initial = 24.7 °C - 22.3 °C = 2.4°C

(c) ΔH

$\begin{array}{ccccl}n\Delta H & +& mC \Delta T& = &0\\\text{0.066 667 mol }\times \Delta H& + & \text{116.667 g} \times 1.10 \text{ J$^{\circ}$C$^{-1}$g$^{-1}$} \times 2.4 \, ^{\circ}\text{C} & = & 0\\0.066667 \Delta H \text{ mol} & + & \text{310 J} & = & 0\\&&0.066667 \Delta H \text{ mol} & = & \text{-310 J} & & \\\end{array}\\$

$\begin{array}{ccccl}& &\Delta H & = & \dfrac{\text{-310 J}}{\text{0.066667 mol}}\\\\& &\Delta H & = & \textbf{-4600 kJ/mol}\\\end{array}\\\large \boxed{\mathbf{\Delta_{\textbf{r}}H} =\textbf{-4600 J$\cdot$ mol}^{\mathbf{-1}}}$

This result appears nonsensical, but it is derived from your given figures.

6 0

1 month ago