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uranmaximum [27]
4 years ago
10

.Photography first used at a crime scene. before the 1800s during the 1800s 1900-1988 1990-present

Chemistry
2 answers:
laila [671]4 years ago
6 0

Answer:

during the 1800s

Explanation:

Alphonse Bertillon (a French police officer) was the first to methodically photograph and document crime scenes. He is also the inventor of the mug shot.

Photographs at crime scenes and criminals started at mid-1800s and they were standardized at the end of that century when they came to be widely accepted as a forensic means of identification.

sveticcg [70]4 years ago
5 0
I'm going to say during the 1800s
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and amounts of reactants: 2.01 g salicylic acid + 5.00 mL acetic anhydride (plus 5 drops of 85% phosphoric acid) a) If the densi
irakobra [83]

Answer:

see explanation below

Explanation:

Now. According to the context of this problem, I'm assuming you are doing the synthesis reaction of aspirin, which is a 1:1 ratio and the reaction is:

C7H6O3 + C4H6O3 ------> C9H8O4 + CH3COOH

Now that we know the general reaction, first, let's get the mass of acetic anhydride

m = d*V = 1.08 * 5 = 5.4 g

Now, with the molar mass of each reactants:

MM of SA = 138.12 g/mol

MM of AA = 102.09 g/mol

MM of aspyrin = 180.16 g/mol

Let's calculate now the moles:

moles of SA = 2.01 / 138.12 = 0.015 moles

moles of AA = 5.4 / 102.09 = 0.053 moles

As we can see in the reaction, 1 mole of SA reacts with 1 mole of AA but we have 0.015 of SA and 0.053 of AA, This means that the limiting reagent is the SA, therefore, it will be the first to be consumed in the reaction.

Now the theorical yield of Aspirin is:

m = 0.015 * 180.16 = 2.7024 g

The purpose of the phosphoric acid is to convert the anhydride acetic into an acid form, therefore, the Salycid acid (The OH) can act as nucleophile and react with the carbonile of the anydride. In this way, we can form the aspirin,

6 0
3 years ago
Naming the hydrates?
slamgirl [31]
HEY mate here your answer

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8 0
4 years ago
Read 2 more answers
help please. What type of reaction is this: barium nitrate --> barium oxide + nitrogen dioxide + oxygen
Anon25 [30]

Answer:

Decomposition Reaction

Explanation:

Ba(NO₃)₂(s) ⇒ BaO(s) + N₂(g) + 3 O₂(g)

Barium nitrate decomposes into the chemical species that were used to create it.

3 0
3 years ago
Calculate the wavelength of a red light beam with a frequency of 2.3x10^-3 Hz .
Leno4ka [110]

Divide the energy by Planck's constant, 6.626 x 10-34, to get the frequency of the wave. Divide the speed of light, ~300,000,000 m/s, by the frequency to get wavelength.

<em>(wrong Subject Selection)</em>

8 0
3 years ago
Given the following equation: H2(g)+F2(g)=2HF(g)
Lelu [443]

Answer:

200grams

Explanation:

The balanced chemical equation for this reaction is given as follows:

H2(g)+F2(g) → 2HF(g)

This equation shows that it takes 1 mol of both hydrogen gas (H2) and fluorine gas (F2) to produce 2 moles of hydrogen fluoride (HF)

Hence, 5 moles of fluorine gas (F2) will produce 5 × 2 = 10 moles of HF.

In order to convert the mole value of HF to gram value, we use the following formula;

Mole = mass/molar mass

Molar mass of HF = 1 + 19 = 20g/mol

mass = mole × molar mass

mass = 10 × 20

mass = 200grams of HF.

8 0
3 years ago
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