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stepladder [879]
2 years ago
7

Why is gunshot residue important for a forensic scientist? What are the potential complications with this type of evidence?

Chemistry
2 answers:
Jlenok [28]2 years ago
5 0

Answer 1: A gun shot residue is the powdery discharge that release after the firing process of the firearm. The powdery discharge consists of unburnt or partially burnt primer, propellants, fragments of the projectiles, cartilage cases  and residues present inside the firearm.

It is important for the forensic scientists so as to detect the culprit as these residues are left on the clothes and hands after firing. It can be used to identify the direction and distance of firing.

Answer 2: The complications associated with gunshot residue are:

1. The particles are very small and may exhibit low density they are likely to blow by wind so they may not be found at some crime scene.

2. As the powdery discharge consists of explosive particles in small amounts but on testing can explode and can cause harm.

erik [133]2 years ago
3 0
A residue from a gunshot is most likely gun powder, which tells you what kind of bullet was shot and the type of gun that was used to shoot the target/victim/person. Some complications may be that there is more than one gun or weapon which uses that residue, so it may be hard to pinpoint it and the bullet can't really tell you who it is unless there's DNA on the bullet, and the chemicals of the bullet may even destroy evidence.
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112 g of aluminum carbide react with 174 g water to produce methane and aluminum hydroxide in the reaction shown below.
dolphi86 [110]

<u>Answer:</u> 4.999 moles of excess reactant will be left over.

<u>Explanation:</u>

Limiting reagent is defined as the reagent which is completely consumed in the reaction and limits the formation of the product.

Excess reagent is defined as the reagent which is left behind after the completion of the reaction.

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}}       .....(1)

Given mass of aluminium carbide = 112 g

Molar mass of aluminium carbide = 143.96 g/mol

Putting values in equation 1:

\text{Moles of aluminium carbide}=\frac{112g}{143.96g/mol}=0.778mol

For the given chemical reaction:

2Al_4C_3(s)+12H_2O(l)\rightarrow 3CH_4(g)+4Al(OH)_3(s)

By the stoichiometry of the reaction:

2 moles of aluminium carbide reacts with 12 moles of water

So, 0.778 moles of aluminium carbide will react with = \frac{12}{2}\times 0.778=4.668 mol of water

Given mass of water = 174 g

Molar mass of water = 18 g/mol

Putting values in equation 1:

\text{Moles of water}=\frac{174g}{18g/mol}=9.667mol

Moles of excess reactant (water) left = 9.667 - 4.668 = 4.999 moles

Hence, 4.999 moles of excess reactant will be left over.

8 0
2 years ago
Tin(ii) fluoride (snf2) is often added to toothpaste as an ingredient to prevent tooth decay. what is the mass of f in grams in
a_sh-v [17]
From the periodic table:
molar mass of Sn = 118.71 grams
molar mass of F = 18.99 grams

This means that:
molar mass of SnF2 = 118.71 + 2(18.99) = 156.69 grams

Therefore, 156.69 grams of SnF2 contains 37.98 grams of F. To know the amount of F in 36.5 grams of the compound, we will simply do a cross multiplication as follows:
mass of F = (36.6 x 37.98) / 156.69 = 8.847 grams
3 0
3 years ago
Calculate the pOH of a 0.0143 M NaOH solution at 25 ⁰C.
arsen [322]

Answer:

A.) 1.845

Explanation:

You can find the pOH using the following equation:

pOH = -log[OH⁻]

Since NaOH dissociates into 1 Na⁺ and 1 OH⁻, the concentration of both ions is 0.0143 M.

pOH = -log[OH⁻]

pOH = -log[0.0143]

pOH = 1.845

5 0
2 years ago
Please answer my questions. I really need them soon. I will post the links for other questions in the comments.
Assoli18 [71]

Explanation:

option option B is the correct answer of given statement helium-4(He)=2

6 0
2 years ago
How does the plate boundary along the west coast of the United States change over time?
Tanzania [10]

The North American plate is moving towards the west-southwest at about 2.3 centimeters every year mediated by the Mid-Atlantic Ridge, the spreading center, which gave rise to the Atlantic Ocean. The small Juan De Fuca plate, moving east-northeast at 4 centimeters every year, was once a component of much greater oceanic plates known as the Farallon plate.  

The Farallon plate used to comprise what is now the Cocos plate of Mexico and Central America, and the Juan de Fuca plate in the region from N. Vancouver Island to the Cape Mendicino California, and a big sea floor tract in between. However, the middle portion of the Old Farallon plate disappeared underneath North America, it was subducted underneath California leaving the San Andreas fault system behind as the contact between the Pacific plates and North America.  

The Juan De Fuca plate is still actively subducting underneath North America. Its movement is not smooth, however, rather sticky. The buildup of strain takes place until the fault dissociates and a few meters of Juan De Fuca get slid underneath North America in a big earthquake.  


7 0
3 years ago
Read 2 more answers
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