Search our library of Chemistry questions

Top answers

Chemistry

All levels

Given the mass number of Aluminium is 27 and the mass number of Oxygen is 16, how many moles of Al2O3 are in 30g? (3 significant figures)

Molar Mass of Al₂O₃ = 27+27+16+16+16 = 102Mass = mol*Mr so mol = Mass/Mrmol = 30/102 = 0.294117... = 0.294 moles

2913 Views

If 9g of alumnium reacts with 35.5g of chlorine, what is the empirical formula of the compound formed?

Empirical formulaThe empirical formula is a formula giving the proportions of the elements present in a compound but not the actual numbers or arrangement of atoms. To find this you require the mas...

Answered by Beatrice F. • Chemistry tutor

6277 Views

What is an isotope?

Isotopes are atoms of an element with different numbers of neutrons. They have the same proton number, but different mass numbers. They have the same chemical properties, due to having the same number of ...

Answered by Beatrice F. • Chemistry tutor

3824 Views

A buffer solution is made with a pH of 5.000. Solid sodium ethanoate, CH3COONa, is added to 400 cm^3 of 0.200 mol dm^–3 ethanoic acid (Ka = 1.75 × 10^–5 mol dm^–3). Calculate the mass of sodium acetate that must be dissolved in the acid to prepare this

There are three steps:
Calculate [CH₃COO^–] using the equation for K_aCalculate the moles of CH₃COO^– using the equation concentration = moles/volu...

Answered by Felix B. • Chemistry tutor

14085 Views

Explain the trend in melting points of the period 3 elements

There are four main areas we need to consider in answering this question. The first is Sodium, Magnesium and Aluminium. These are all metals and so have a metallic bonding structure. As you go across the ...

Answered by Lloyd M. • Chemistry tutor

48923 Views