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Ymorist [56]
3 years ago
11

Calculate the heat change associated

Chemistry
1 answer:
alexgriva [62]3 years ago
7 0

Answer:

Heat change is -14,175 joules, Exothermic

Explanation:

We are given;

  • Mass of aluminium bar as 350.0 g
  • initial temperature as 70.0 °C
  • Final temperature as 25 °C

We are required to determine the heat change and indicate whether endothermic or exothermic;

We know that;

Heat change = Mass of a substance × specific heat × change in temperature

In this case;

Mass of Aluminium = 350.0 g

Change in temperature = (25 - 70)

                                       = -45° C

Specific heat of aluminium = 0.90 J/g°C

Therefore;

Heat change = 350.0 g × 0.90 J/g°C × -45°C

                     =-14,175 joules

The heat change is exothermic because it is a negative value, also because cooling process involves heat loss and thus an exothermic reaction.

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aksik [14]
Density is mass over volume. If you put it into a formula it would look like this:

D = \frac{m}{v}

Based on the problem given, you can see that the mass of the aluminum block is 82.0 g and the volume is 12.8 cm3. Just put that into your equation and solve for it:

D = \frac{m}{V}=  \frac{82.0g}{12.8cm^{3} }  = 6.4g/ cm^{3}

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4 years ago
How many electrons in an atom can have a quantum number of n = 2?
yuradex [85]
It would be 18 electrons i think 
4 0
3 years ago
In this lab, you are to carry out the formation of a Grignard reagent from 1-bromo-benzene andits subsequent reaction with solid
yan [13]

Answer:

(A). C6H5Br + Mg(in ether) -----------> C6H5MgBr.

(B). C6H5MgBr + O = C = O -----------> C6H5-COO^- Mg^+ Br.

(C). C6H5-COO^- Mg^+ Br + HCl --------> C6H5-COOH + Mg^+Br(OH).

PRODUCTS=> C6H5-COOH and Mg^+Br(OH).

Explanation:

A Grignard reagent is a reagent that/which is an organometallic compound that is R -Mg- X. The R = alkyl, vinyl or allyl and the X = halogens.

It must be noted that an important reaction of Grignard reagent is its reaction with compounds containing the Carbonyl that is -CO functional group and this kind of Reaction is known as a Grignard Reaction.

So, in this question we are told that;

=> "1-bromo-benzene andits subsequent reaction with solid carbon dioxide (CO2) followed by acidic workup (using HCl asthe acid). "

Thus;

(A). C6H5Br + Mg(in ether) -----------> C6H5MgBr.

(B). C6H5MgBr + O = C = O -----------> C6H5-COO^- Mg^+ Br.

(C). C6H5-COO^- Mg^+ Br + HCl --------> C6H5-COOH + Mg^+Br(OH).

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In the ammonium ion 4H atoms are connected to N. 
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the overall charge of NH4 is +1
Charge of N (+) +4 =  +1
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8 0
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