Gases are unique because it is the only phase that

10. A small gold nugget has volume of 0.87 cm3. What is its mass if the density of gold is 19.3 g/cm3?

bulgar [2K]

Answer:

16.791 grams

Explanation:

The density formula is:

$d=\frac{m}{v}$

Rearrange the formula for m, the mass. Multiply both sides of the equation by v.

$d*v=\frac{m}{v}*v$

$d*v=m$

The mass of the gold nugget can be found by multiplying the density and volume. The density is 19.3 grams per cubic centimeter and the volume is 0.87 cubic centimeters.

$d= 19.3 g/cm^3\\v-0.87 cm^3$

Substitute the values into the formula.

$m=d*v$

$m= 19.3 g/cm^3*0.87 cm^3$

Multiply. Note that the cubic centimeters, or cm³ will cancel each other out.

$m=19.3 g*0.87$

$m=16.791 g$

The mass of the gold nugget is 16.791 grams.

8 0

3 years ago

Green light has a wavelength of 550nm. What is the frequency of a photon of green light?

Vikki [24]

Answer:- Frequency is $5.4*10^1^4Hz$ .

Solution:- frequency and wavelength are inversely proportional to each other and the equation used is:

$\nu =\frac{c}{\lambda }$

where, $\nu$ is frequency, c is speed of light and $\lambda$ is the wavelength.

Speed of light is $3.0*10^8m/s$ .

We need to convert the wavelength from nm to m.

( $1nm=10^-^9m$ )

$550nm(\frac{10^-^9m}{1nm})$

= $5.5*10^-^7m$

Now, let's plug in the values in the equation to calculate the frequency:

$\nu =\frac{3.0*10^8m.s^-^1}{5.5*10^-^7m}$

= $5.4*10^1^4s^-^1$ or $5.4*10^1^4Hz$

since, $1s^-^1=1Hz$

So, the frequency of the green light photon is $5.4*10^1^4Hz$ .

4 0

3 years ago

A mole of any substance contains ___ particles.

Vika [28.1K]

One mole of a substance is equal to 6.022 × 10²³ units of that substance (such as atoms, molecules, or ions). The number 6.022 × 10²³ is known as Avogadro's number or Avogadro's constant.

7 0

3 years ago

A buffer solution contains 0.496 M hydrocyanic acid and 0.399 M sodium cyanide . If 0.0461 moles of sodium hydroxide are added t

pochemuha

Answer : The pH of the solution is, 9.63

Explanation : Given,

The dissociation constant for HCN = $pK_a=9.31$

First we have to calculate the moles of HCN and NaCN.

$\text{Moles of HCN}=\text{Concentration of HCN}\times \text{Volume of solution}=0.496M\times 0.225L=0.1116mole$

and,

$\text{Moles of NaCN}=\text{Concentration of NaCN}\times \text{Volume of solution}=0.399M\times 0.225L=0.08978mole$

The balanced chemical reaction is:

$HCN+NaOH\rightarrow NaCN+H_2O$

Initial moles 0.1116 0.0461 0.08978

At eqm. (0.1116-0.0461) 0 (0.08978+0.0461)

0.0655 0.1359

Now we have to calculate the pH of the solution.

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

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

$pH=9.31+\log (\frac{0.1359}{0.0655})$

$pH=9.63$

Therefore, the pH of the solution is, 9.63

4 0

4 years ago

State the types of change that take place in each of the following

atroni [7]

Answer:

Chemical changes

Explanation:

a)Burning a piece of charcoal - chemical change

b) Heating copper (ii) carbonate strongly - chemical change

c) Heating Zinc oxide strongly - chemical change

The given types of reaction indicates chemical changes. A chemical change is one in which a new kind of matter is formed. It is always accompanied by energy changes. The process is not easily reversible and hence, it is a permanent procedure.

Burning of charcoal produces a new kind of produces in the combustion process.

Both heating of copper(ii)carbonate strongly and zinc oxide will lead to a decomposition reaction in which new compounds are formed.

4 0

3 years ago