Determine the empirical formula of kevlar, used in making bullet proof vests, is 70.6% c, 4.2% h, 11.8% n and 13.4% o.

Assuming a basis of 100 g of Kevlar, therefore the masses are:

C = 70.6 g

H = 4.2 g

N = 11.8 g

O = 13.4 g

We know the molar masses are:

C = 12.01, H = 1.008, N = 14.01, O = 16.00

Calculating for the moles per element:

C = 70.6 / 12.01 = 5.88 mol

H = 4.2 / 1.008 = 4.17 mol

N = 11.8 / 14.01 = 0.84 mol

O = 13.4 / 16 = 0.84 mol

To get the empirical formula, the next step is to divide everything by the smallest moles = 0.84. So:

C = 7

H = 5

N = 1

O = 1

Hence the empirical formula is:

C7H5NO

answer: a tank of height h is filled with water and sits on the ground. water squirts from a hole at a height y above the ground and has a range r. for two y values, 0 and h, r is zero. determine the value of y for which the range will be a maximum.

explanation:

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.