chapter 11 Flashcards
(25 cards)
chemical changes can be identifies by
heat or light produced, gas produced,percipitate formed, colour change
qualities of chemical changes
not easily reversable, new substance formed
qualities of physical changes
easily reversible, no new substance formed
what is combustion
combustion is when a substance reacts with oxygen when heated.
what is thermal decomposition
thermal decomposition is when a single substance is breaks down into two or more simpler substances when heated
what is oxidation
addition of oxygen in the substance
explain magnesium (burns in the air) + oxygen = magnesium oxide
what type of chemical change is this?
The reaction is both a combustion( magnesium reacts with oxygen and burns in the air) and oxidation ( oxygen is added to the magnesium)
what is netrualisation
neutralisation is when acid and alkali reacts to form salt and water
what happens to acids when dissolved in water
It produces hydrogen ions
what does acids taste like
it is sour and is often found in fruits
what does alkalis produce when dissolved into water
it produces hydroxide ions
what does alkalis feels like
soapy
what is the PH levels of acids
lesser than PH7 and the strength of acid increases when the PH level decreases
What is the PH level of alkaline
greater than PH7 and the strength of alkaline increase when the PH level increases
what colour does the red and bluelitmus paper turn when in contact with acids and alkaline
red litmus paper remains red when in contact with acid and turns blue when in contact with alkaline
what colour does the universal indicator turn when in PH 0
it changes into dark red
what colour does the universal indicator turn into when at PH14
it changes into violet
what colour does the universal indicator turn into when at PH 7
it changes into green
what is produced when acid and alkalis reacts with each other
salt and water is produced
what is produced when acid reacts with metal
salt and hydrogen is produced
what is produced when acid reacts with metal carbonate
salt, water and carbon dioxide is produced
how do you test for hydrogen
place a lighted splint near the gas and if the lighted splint is extinguished, with a pop sound, hydrogen is persent. Because hydrogen gas is very flammable.
how do you test for carbon dioxide
bubble gas into lime water( calcium hydroxide). If white percipiate is formed in the water, carbon dioxide is present
what is salt
salt are netural compounds
