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Sophie [7]
3 years ago
13

How much energy is needed to melt 47.6g of water

Chemistry
1 answer:
Rasek [7]3 years ago
5 0

Answer:

15.9 kJ

Explanation:

Use the equation q = nΔH

q = (47.6)(334)

q = 15898.4 J

or 15.9 kJ

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A cup of gold colored metal beads was measured to have a mass 425 grams. By water displacement, the volume of the beads was calc
Troyanec [42]

Given parameters;

Mass of gold colored metal beads  = 425g

Volume of water displaced by beads = 48.0cm³

Unknown;

Identity of the metal = ?

Given densities;

Gold: 19.3 g/mL

Copper: 8.86 g/mL

Bronze: 9.87 g/mL

Density is an intensive property of any substance. This implies that we can use the density of any substance to identify it.

Density can be defined as the mass per unit volume of a substance. Every substance has a unique mass per volume.

 Mathematically;

                    Density  = \frac{mass}{volume}

where mass is in kg or g

           volume is in  m³ or cm³

To find the density, we must know the mass and volume.

In this problem, the volume of the gold metal beads is the same as the volume of water displaced. This is a way to measure volume of solids.

Since the volume is given in cm³, and we are comparing with choices that have units in g/mL, we simply convert the volume in cm³ to mL

                   1cm³  = 1mL³

So therefore, volume of gold colored metal is 48mL

Now input the parameters given and solve for the density;

           Density  = \frac{425g}{48mL }    = 8.85g/mL

From the given densities, we clearly see that copper is the metal since they both of similar densities.

4 0
3 years ago
Suppose 40.8g of copper(II) acetate is dissolved in 200.mL of a 0.70 M aqueous solution of sodium chromate.
Contact [7]

Answer:

0.42 M

Explanation:

The reaction that takes place is:

  • Cu(CH₃COO)₂ + Na₂CrO₄ → Cu(CrO₄) + 2Na(CH₃COO)

First we <u>calculate the moles of Na₂CrO₄</u>, using the <em>given volume and concentration</em>:

(200 mL = 0.200L)

  • 0.70 M * 0.200 L = 0.14 moles Na₂CrO₄

Now we <u>calculate the moles of Cu(CH₃COO)₂</u>, using its <em>molar mass</em>:

  • 40.8 g ÷ 181.63 g/mol = 0.224 mol Cu(CH₃COO)₂

Because the molar ratio of Cu(CH₃COO)₂ and Na₂CrO₄ is 1:1, we can directly <u>substract the reacting moles of Na₂CrO₄ from the added moles of Cu(CH₃COO)₂</u>:

  • 0.224 mol - 0.14 mol = 0.085 mol

Finally we <u>calculate the resulting molarity</u> of Cu⁺², from the <em>excess </em>cations remaining:

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4 0
3 years ago
matter is passed down from the living part of an ecosystem to the non living part when witch of the following take place ?
Ivenika [448]
I don’t know about that
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3 years ago
NaCl has a mc020-1.jpgHfus = 30.2 kJ/mol. What is the mass of a sample of NaCl that needs 732.6 kJ of heat to melt completely?
lilavasa [31]

Answer: The mass of the sample will be 1417.7 grams.

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1 mole of NaCl has a mass of 58.44 grams.

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So, 732.6 kJ of heat will be required for = \frac{58.44g}{30.2kJ}\times 732.6 kJ = 1417.65 grams of NaCl.

Hence, the mass of NaCl sample will be 1417.7 grams.

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4 years ago
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I can’t see any this what the question
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