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2 years ago

15

Do Alkali Metal Compounds form precipitates? And Why?

1 answer:

Alexeev081 [22]2 years ago

6 0

Answer:

Alkali metal hydroxides can be used to test the identity of metals in certain salts. The colour of the precipitate will help identify the metal : Calcium hydroxide is soluble; no precipitate is formed.

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Kate gathered three boxes of the same size made of different materials: glass, clear plastic, and aluminum painted black. She pl

zalisa [80]

<h2>Answer:</h2>

Correct option is B.

B. To relate the type of box material to the warmth of air within the box.

<h2>Explanation:</h2>

Kate gathered three boxes of the same size made of different materials: glass, clear plastic, and aluminum painted black. She placed them on a window sill in the sun for an hour and then measured the warmth of the air in each box. She actually did this to relate the type of box material to the warmth of air within the box.

6 0

3 years ago

Instant cold packs, often used to ice athletic injuries on the field, contain ammonium nitrate and water separated by a thin pla

RSB [31]

<u>Answer:</u> The enthalpy change of the reaction is -27. kJ/mol

<u>Explanation:</u>

To calculate the mass of water, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Density of water = 1 g/mL

Volume of water = 25.0 mL

Putting values in above equation, we get:

$1g/mL=\frac{\text{Mass of water}}{25.0mL}\\\\\text{Mass of water}=(1g/mL\times 25.0mL)=25g$

To calculate the heat released by the reaction, we use the equation:

$q=mc\Delta T$

where,

q = heat released

m = Total mass = [1.25 + 25] = 26.25 g

c = heat capacity of water = 4.18 J/g°C

$\Delta T$ = change in temperature = $T_2-T_1=(21.9-25.8)^oC=-3.9^oC$

Putting values in above equation, we get:

$q=26.25g\tiimes 4.18J/g^oC\times (-3.9^oC)=-427.9J=-0.428kJ$

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of ammonium nitrate = 1.25 g

Molar mass of ammonium nitrate = 80 g/mol

Putting values in above equation, we get:

$\text{Moles of ammonium nitrate}=\frac{1.25g}{80g/mol}=0.0156mol$

To calculate the enthalpy change of the reaction, we use the equation:

$\Delta H_{rxn}=\frac{q}{n}$

where,

q = amount of heat released = -0.428 kJ

n = number of moles = 0.0156 moles

$\Delta H_{rxn}$ = enthalpy change of the reaction

Putting values in above equation, we get:

$\Delta H_{rxn}=\frac{-0.428kJ}{0.0156mol}=-27.44kJ/mol$

Hence, the enthalpy change of the reaction is -27. kJ/mol

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3 years ago

1. How many hydrogen atoms are in 5 molecules of isopropyl alcohol, C3H7O

Gekata [30.6K]

1. c. 35
2. <span>d. 1.26 x 10^24 molecules
3. </span><span>d. 303.6 g</span>

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3 years ago

Read 2 more answers

What is a ionic conmpound?

Anna [14]

A chemical compound made up of ions by forces that create ionic bonding. It is a neutral compound.

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3 years ago

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babunello [35]

D.mno4- is reuced it loses h atom

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3 years ago