All categories

3 years ago

I need help with the first question what the answer?

Chemistry

1 answer:

Margaret [11]3 years ago

8 0

Answer:

Density is 2.7 grams

Explanation:

formula for density is p= mass over volume [p being density]. So all you have to do is divide

You might be interested in

The production of a gas when acid is added to a sample of chalk is an indication of what type of reaction

ahrayia [7]

It is a result of a chemical reaction.

5 0

3 years ago

Read 2 more answers

Calcium nitrate tetrahydrate dissolves in cold water to the extent of 266 g per 100 cm3. What is the concentration of nitrate io

Soloha48 [4]

Answer : The correct option is, (b) 22.5 M

Explanation : Given,

Mass of calcium nitrate tetrahydrate = 266 g

Molar mass of calcium nitrate tetrahydrate = 236.15 g/mole

Volume of solution = $100cm^3=100mL$

Molarity : It is defined as the moles of solute present in one liter of solution.

Formula used :

$Molarity=\frac{\text{Mass of calcium nitrate tetrahydrate }\times 1000}{\text{Molar mass of calcium nitrate tetrahydrate }\times \text{volume of solution in ml}}$

Now put all the given values in this formula, we get:

$Molarity=\frac{266g\times 1000}{236.15g/mole\times 100ml}=11.26mole/L=11.26M$

As calcium nitrate tetrahydrate dissociate to give 1 mole of calcium ion, 2 moles of nitrate ion and 4 moles of water.

The concentration of nitrate ion = $2\times 11.26M=22.5M$

Thus, the concentration of nitrate ion is, 22.5 M

4 0

3 years ago

Convert the composition of the following alloy from atom percent to weight percent (a) 44.9 at% of silver, (b) 46.3 at% of gold,

vesna_86 [32]

Answer:

Mass percentage of gold : 33.35%

Mass percentage of silver: 62.80%

Mass percentage of copper : 3.85%

Explanation:

$N=n\times N_A$

Where : N = Number of atoms

n = moles

$N_A=6.022\times 10^{23}$ = Avogadro number

Let the total atoms present in the alloy be 100.

Atom percentage of silver = 44.9%

Atoms of of silver = 44.9% of 100 atoms = 44.9

Atomic weight of silver = 107.87 g/mol

Mass of 44.9 silver atoms = 107.87 g/mol × 44.9 = 4,843.363 g/mol

Atom percentage of gold= 46.3%

Atoms of of gold = 46.3% of 100 atoms = 46.3

Atomic weight of gold = 196.97 g/mol

Mass of 44.9 gold atoms = 196.97 g/mol × 46.3 = 9,119.711 g/mol

Atom percentage of copper = 8.8 %

Atoms of of copper = 8.8% of 100 atoms = 8.8

Atomic weight of copper = 63.55 g/mol

Mass of 44.9 copper atoms = 63.55 g/mol × 8.8 = 559.24 g/mol

Total mass of an alloy :4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol

Mass percentage of gold :

$\frac{4,843.363 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=33.35 \%$

Mass percentage of silver:

$\frac{9,119.711 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=62.80\%$

Mass percentage of copper :

$\frac{559.24 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=3.85\%$

7 0

3 years ago

Paul has different spoons for cooking. He told Sue that he likes to stir hot food with a wooden spoon because it does not burn h

IceJOKER [234]

Answer:

Sue was not right as wood is not a heat conductor and will not allow heat to pass through the spoon thus keeping the hand safe. In a meatal spoon, heat can pass through and burn the hand as meatal is a good conductor of heat.

8 0

3 years ago

An atom has two valence electrons, but four shells. This element is a member of which group or family?

Vesna [10]

The correct answer is C: the alkaline earth metals!

8 0

2 years ago