All categories

3 years ago

Which sample contains the same number of atoms as a gram-atomic mass of He?

Chemistry

1 answer:

JulijaS [17]3 years ago

4 0

Answer: 2. 7g of Li

Explanation: A mole of any substance contains the same number of particles (Avogadro's number, 6.02*10^23). 1 gram atomic mass of He (4g) is equivalent to 1 mole; so is 1 gram atomic mass (7g) of Li

You might be interested in

a brick measures 25cm by 12cm by 13cm. What is the volume of the brick in cm cubed? how many milliliters of water would this bri

julia-pushkina [17]

The volume is 3900cm^3 and the bricks density is 3900 ml

5 0

3 years ago

Magnesium has three naturally occurring isotopes with masses of 23.99, 24.99, and 25.98 amu and natural abundances of 78.99%, 10

Darya [45]

Atomic mass of magnesium = (23.99 x 78.99%) + (24.99 x 10.00%) + (25.98 x 11.01%)
= 24.31 g/mol

5 0

4 years ago

Pllllzzzzzz help

Nookie1986 [14]

TMS has 12 protons which are all equivalent and four carbons, which are also all equivalent. This means that it gives a single, strong signal in the spectrum, which turns out to be outside the range of most other signals, especially from organic compounds.

8 0

3 years ago

The amount ofcalcium present in milk can be determined by adding oxalate to asample and measuring the massof calcium oxalate pre

Sauron [17]

<u>Answer:</u> The mass percent of calcium in milk is 0.107 %

<u>Explanation:</u>

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

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

Given mass of calcium oxalate = 0.429 g

Molar mass of calcium oxalate = 128.1 g/mol

Putting values in equation 1, we get:

$\text{Moles of calcium oxalate}=\frac{0.429g}{128.1g/mol}=0.0033mol$

The given chemical equation follows:

$Na_2C_2O_4(aq.)+Ca^{2+}(aq.)\rightarrow CaC_2O_4(s)+2Na^+(aq.)$

Sodium oxalate is present in excess. So, it is considered as an excess reagent. And, calcium ion is a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of calcium oxalate is produced from 1 mole of calcium ion

So, 0.0033 moles of calcium oxalate is produced from = $\frac{1}{1}\times 0.0033=0.0033mol$ of calcium ions

Now, calculating the mass of calcium ions by using equation 1, we get:

Moles of calcium ions = 0.0033 moles

Molar mass of calcium ions = 40 g/mol

Putting values in equation 1, we get:

$0.0033mol=\frac{\text{Mass of calcium ions}}{40g/mol}\\\\\text{Mass of calcium ions}=(0.0033mol\times 40g/mol)=0.132g$

To calculate the mass percentage of calcium ions in milk, we use the equation:

$\text{Mass percent of calcium ions}=\frac{\text{Mass of calcium ions}}{\text{Mass of milk}}\times 100$

Mass of milk = 125 g

Mass of calcium ions = 0.132 g

Putting values in above equation, we get:

$\text{Mass percent of calcium ions}=\frac{0.132g}{125g}\times 100=0.107\%$

Hence, the mass percent of calcium in milk is 0.107 %

7 0

3 years ago

Most matter is made up of _____, rather than single _____.

bixtya [17]

Answer:

molecules, elements

Explanation:

molecules are a mix of elements

7 0

2 years ago