If bell peppers and hot peppers are planted next to each other will the bell peppers become hot also? I planted them about 1 1/2 feet apart.
No. That trait is only passed to the next generation, not inherited into the tastes/flavors of the fruit you're going to pick off your plants that are currently growing.
If you collect the seed from the peppers and grow them out the "sweet" peppers might become hot -if- they cross pollinated with a hot pepper.
NC is correct. Heat is genetic. The pepper fruit is produced by the plant itself, not the seeds, so it will always use the genetics of the mother plant.
There is absolutely no way to make a sweet pepper hot short of genetically engineering some kind of retrovirus to change it's DNA.
Its the seeds from those peppers that, if saved and planted next year, may be hybrids that will have hot fruit.