Write the formulas of the compounds formed by nh4+ with the following anions: cn−, clo3−, so32−, h2po4−. express your answers as chemical formulas separated by commas. use the given order of anions.

2)

write the formulas of the compounds formed by al3+ with the following anions: cn−, clo3−, so32−, h2po4−.

express your answers as chemical formulas separated by commas. use the given order of anions.

The formula of the ionic compounds formed when ions combine depends on the magnitude of charge or valency on each of the combining ions.

For an ionic compound, the formula of the compound shows us the ratio of ions in a formula unit of the compound.

We must note that this formula is reflective of the magnitude of charges or valency carried by each of the ions in the formula.

With , the compounds formed are as follows;

NH4CN, NH4ClO3, (NH4)2SO3, NH4H2PO4

With the compounds form are;

Al(CN)3, Al(ClO3)3, Al2(SO3)3, Al(H2PO4)3

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Explanation:

Cations (positive ions) and anions (negative ions) combine to form ionic compounds. The charge of each ion is stated as the superscript in its formula.

The final compounds should be neutral (not carrying charge.) For that to happen, the ions should combine at a ratio that allows their charges to balance.

By convention, in chemical formula of ionic compounds, cations are written before anions.

The charge on an Al³⁺ cation is +3. The charge on a SO₃²⁻ anion is -2.

Start by finding the least common multiple of the absolute value of the charges (drop the negative sign in front of the charge.)

.

The number of Al³⁺ ions in a formula unit of this compound will be equal to

.

Similarly, the number of SO₃²⁻ ions in a formula unit of this compound will be equal to

.

If a polyatomic ion (an ion with more than one atoms in it) appears more than once in the formula, enclose it in brackets and write the number of its occurrence outside the bracket.

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Apply this rule to find the formula of other compounds. Additionally, keep in mind that if the charge on the cation and the anion is the same, each should occur only once in the formula.

pre-sliced bread is a relatively recent development in baking technology. previous to that, it was always sold in a bakery in daily-made contiguous loaves with no wrapping, and was moderately perishable, usually being used with a day or two (which is why every bakery had a discounted “day-old” bread table.) therefore, pre-sliced bread would grow stale quickly. the hard crust provided a protective layer, and once the exposed dry slice left from the previous cut was removed, the interior was still soft.

what keeps bread soft is the moisture retained in the crumb (the light spongy part that’s not crust). the reason the crust develops is the surface of the dough gets exposed to hot dry air during baking which browns the outer layer and seals it, preventing all the moisture from escaping the dough. longer exposure to air will also eventually cause your bread to lose flavor and become stale.

people were used to cutting slices as they needed them and storing bread in a specially-made wooden or metal breadbox or pail with a lid to preserve it longer, but the first automatically sliced commercial loaves were produced on july 6, 1928, in chillicothe, missouri, using a machine invented by otto rohwedder, an iowa-born, missouri-based jeweler.[1] pre-sliced bread would indeed dry out, were it not for another 20th century technology: the plastic bag. bread could now be pre-sliced, and if the enclosing bag remains sealed as much as possible, the bread will remain soft and fresh for longer than if sitting unwrapped on a shelf or enclosed in a bread box that is not air-tight. sealed packaging meant bread could also be sold on store shelves and eliminate frequent trips to a bakery.

sealing bread in a plastic bag had another effect: the moisture in the loaf will re-distribute into the crust and soften it, which is sometimes more pleasing in a sandwich - especially for children whose teeth might not yet be strong enough to tear through a hard crust. a homemade loaf of bread can be sealed in a bag overnight and the crust will become soft like store-bought sandwich bread.

these were novel changes in how bread was produced and sold, which led to the coining of the phrase “the greatest thing since sliced bread.”