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tester [92]
3 years ago
5

A student dissolves 13.8g of sodium chloride in of water in a well-insulated open cup. He then observes the temperature of the w

ater fall from 20°C to 19.1° over the course of 5.1 minutes. Use this data, and any information you need from the ALEKS Data resource, to answer the questions below about this reaction:
NaCl(s) → Na+ (aq) + Cl-(aq)

You can make any reasonable assumptions about the physical properties of the solution. Be sure answers you calculate using measured data are rounded to the correct number of significant digits. Note for advanced students: it's possible the student did not do the experiment carefully, and the values you calculate may not be the same as the known and published values for this reaction.

Is this reaction exothermic, endothermic or neither?
If you said the reaction was exothermoc or endothermic, calculate the amount of heat that was released or absorved by the reaction in this case.
Calculate the reaction enthalpy per mole.
Chemistry
1 answer:
Firdavs [7]3 years ago
3 0

Answer:

Exothermic and H=-1.55x10^6

Explanation:

Because the water is changing it is exothermic and the h is also exothermic

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What is the density of a rectangle solid with dimensions
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Answer:

5625000gm/cm^3

Explanation:

volume=w*h*l=25*15*5=1875cm^3

density=mass*volume

=1875*3000

=5625000gm/cm^3

8 0
3 years ago
Please give me the answer please
zepelin [54]

Answer:

A. 30cm³

Explanation:

Based on the chemical reaction:

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

<em>1 mol of calcium carbonate reacts with 2 moles of HCl to produce 1 mol of CO₂</em>

<em />

To solve this question we must convert the mass of each reactant to moles. With the moles we can find limiting reactant and the moles of CO₂ produced. Using PV = nRT we can find the volume of the gas:

<em>Moles CaCO₃ -Molar mass: 100.09g/mol-</em>

1.00g * (1mol / 100.09g) = 9.991x10⁻³ moles

<em>Moles HCl:</em>

50cm³ = 0.0500dm³ * (0.05 mol / dm³) = 2.5x10⁻³ moles

For a complete reaction of 2.5x10⁻³ moles HCl there are necessaries:

2.5x10⁻³ moles HCl * (1mol CaCO₃ / 2mol HCl) = 1.25x10⁻³ moles CaCO₃. As there are 9.991x10⁻³ moles, HCl is limiting reactant.

The moles produced of CO₂ are:

2.5x10⁻³ moles HCl * (1mol CO₂ / 2mol HCl) = 1.25x10⁻³ moles CO₂

Using PV = nRT

<em>Where P is pressure = 1atm assuming STP</em>

<em>V volume in L</em>

<em>n moles = 1.25x10⁻³ moles CO₂</em>

<em>R gas constant = 0.082atmL/molK</em>

<em>T = 273.15K at STP</em>

<em />

V = nRT / P

1.25x10⁻³ moles * 0.082atmL/molK*273.15K / 1atm = V

0.028L = V

28cm³ = V

As 28cm³ ≈ 30cm³

Right option is:

<h3>A. 30cm³</h3>

5 0
3 years ago
What will you observe if you add cuso4 to a solution containing glucose?
arsen [322]
The blue color of copper (ii) sulfate will change to green, yellow, orange ,red and then a dark red or brown.
Glucose is a reducing sugar; reducing sugars are sugar that forms an aldehyde or ketone in the presence of an alkaline solution. Reducing sugars reduce the blue copper sulfate from the Benedict's solution to a red brown copper sulfide; which is seen as the precipitate and is responsible for the color change. 
7 0
3 years ago
A gas mixture contains 10.0 mole% H2O (v) and 90.0 mole % N2. The gas temperature and absolute pressure at the start of each of
Rainbow [258]

Answer: (a). T = 38.2 °C     (b). V = 1.3392 cm³     (c). ii and iii  

Explanation:

this is quite easy to solve, i will give a step by step analysis to solving this problem.

(a). from the question we have that;

the Mole fraction of Nitrogen, yи₂ = 0.1

Also the Mole fraction of Water, yн₂o = 0.1

We know that the vapor pressure is equal to the partial pressure because the vapor tends to condense at due point.

ρн₂o = ṗн₂o

      = yн₂oP = 0.1 × 500 mmHg = 50 mmHg

from using Antoine equation, we apply the equation

logρн₂o = A - B/C+T

T = B/(A - logρн₂o) - C

  = 1730.63 / (8.07131 - log 50mmHg) - 223.426

T = 38.2 °C

We have that the temperature for the first drop of liquid form is 38.2 °C

(b). We have to calculate the total moles of gas mixture in a 30 litre flask;

   n  = PV/RT  

   n = [500(mmHG) × 30L] / [62.36(mmHGL/mol K) × 323.15K] = 0.744 mol

Moles of H₂O(v) is 0.1(0.744) = 0.0744 mol

Moles of N₂ is 0.9(0.744) = 0.6696 mol

we have that the moles of water condensed is 0.0744 mol i.e the water vapor  in the flask is condensed

Vн₂o = 0.0744 × 18 / 1 (g/cm³)

Vн₂o = 1.3392 cm³

Therefore, the  volume of the liquid water is 1.3392 cm³

(3). (ii) and (iii)

The absolute pressure of the gas and The partial pressure of water in the gas would change if the barometric pressure drops.

cheers i hope this helps!!!!

4 0
3 years ago
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