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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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Organize the following list of atoms from lowest to highest Electronegativity:
Anon25 [30]

Answer:

Barium<Strontium<Calcium <Magnesium< Beryllium

Explanation:

Electronegativity is defined as the ability of an atom in a bond to attract the shared electrons of the bond towards itself.

Electronegativity is a periodic trend that decreases down the group and increases across the period.

Hence, if i want to arrange Beryllium, Barium, Strontium, Magnesium, Calcium in order of increasing electronegativity, i will have;

Barium<Strontium<Calcium <Magnesium< Beryllium

5 0
3 years ago
2. How much heat is released when 432g of water cools down from 710C to 180C?
nadya68 [22]
The heat released by the water when it cools down by a temperature difference AT

is Q = mC,AT

where

m=432 g is the mass of the water

C, = 4.18J/gºC

is the specific heat capacity of water

AT = 71°C -18°C = 530

is the decrease of temperature of the water

Plugging the numbers into the equation, we find

Q = (4329)(4.18J/9°C)(53°C) = 9.57. 104J

and this is the amount of heat released by the water.
7 0
3 years ago
Boron has an average mass of 10.81. One isotope of boron has a mass of 10.012938 and a relative abundance of 19.80 percent. The
Andrej [43]

The average mass of an atom is calculated with the formula:

average mass = abundance of isotope (1) × mass of isotope (1) + abundance of isotope (2) × mass of isotope (2) + ...  an so on

For the boron we have two isotopes, so the formula will become:

average mass of boron = abundance of isotope (1) × mass of isotope (1) + abundance of isotope (2) × mass of isotope (2)

We plug in the values:

10.81 = 0.1980 × 10.012938  + 0.8020 × mass of isotope (2)

10.81 = 1.98 + 0.8020 × mass of isotope (2)

10.81 - 1.98 = 0.8020 × mass of isotope (2)

8.83 = 0.8020 × mass of isotope (2)

mass of isotope (2) = 8.83 / 0.8020

mass of isotope (2) = 11.009975

mass of isotope (1) = 10.012938 (given by the question)

5 0
3 years ago
Which equations are in standard form? Check all that apply
aliya0001 [1]

Answer:

2x+3y=-6

4x+3y=12

3x-y=5

5x+3y=1

Explanation:

standard form: ax + by = C

4 0
3 years ago
HNO3 + H2SO4 + NO
77julia77 [94]

Explanation:

The two half equations are;

3e + HNO3 → NO

S→ H2SO4 + 6e

When balancing half equations, we have to make sure the number of electrons gained is equal to the number of electrons lost.

<em>Which factor will you use for the top equation?</em>

We multiply by 2 to make the number of electrons =  6e

<em>Which factor will you use for the bottom equation?</em>

We multiply by 1 to make the number of electrons = 6e

3 0
2 years ago
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